Italian Jerusalem Artichoke, Leek and Hazelnut Vellutata | Vellutata di Topinambur, Porri e Nocciole
Three Piedmontese things meet in this bowl. A knobbly tuber that Turin eats raw with anchovy sauce, a leek from a single town near Cuneo that has its own autumn fair, and the hazelnut that made the Langhe rich. Together they give a soup that tastes of earth, sweetness and roasted nut at once.
Topinambur is the awkward one. It has almost no starch, so it will not thicken by simmering the way potato or squash does, and its flavour sits between artichoke heart and chestnut with a mineral edge behind it. The body here comes from inulin, the soluble fibre the tuber is full of, released by cooking and broken open by the blender.
Everything else is restraint. A small potato for structure, leeks sweated pale so they sweeten without browning, little enough stock that the purée is never watered down, and cream measured in spoonfuls. The hazelnuts arrive twice, blitzed into the soup and crushed over the top.
Yield: 4 servings. Prep: 25 minutes. Cook: 35 minutes. Total: about 1 hour. Difficulty: intermediate. Course: primo. Region: Piedmont, Cuneo and the Langhe.
The Story
The topinambur is American and its Italian name is a mistake. Helianthus tuberosus reached Europe from Canada at the start of the seventeenth century, and in 1613 a delegation of Tupinamba people from Brazil arrived in Paris to great public excitement. The two novelties were conflated, the tuber took the name of the tribe, and Italy has called it topinambur ever since. Piedmont also calls it ciapinabo, and it was long field food, grown for animals and eaten in hard winters.
Its rehabilitation came through bagna cauda. In the Piedmontese ritual of anchovy, garlic and oil kept warm at the table through a winter evening, raw topinambur is one of the classic vegetables for dipping, valued for a crispness closer to water chestnut than to anything else on the board. Carmagnola and the plain south of Turin still grow it, and the tuber went from peasant filler to regional emblem without ever becoming expensive.
The other two are local aristocrats. The leek of Cervere, a small town in the province of Cuneo, is grown in sandy soil and blanched long, which gives it a white shaft of unusual length and a sweetness that survives cooking; the town holds a leek fair every autumn. The hazelnut is Tonda Gentile Trilobata, the Nocciola Piemonte IGP of the Langhe, the variety that built the confectionery industry of Alba. This soup is simply what those three neighbours do together.
Ingredients
For the vellutata
Jerusalem artichokes, topinambur, scrubbed, 1 1/2 lb (680 g)
Leeks, white and pale green only, 2 large (12 oz, 340 g trimmed)
Yellow potato, peeled and diced small, 5 oz (140 g)
Unsalted butter, 2 tbsp (30 g)
Extra virgin olive oil, 1 tbsp (15 ml)
Light vegetable stock, 3 1/2 cups (830 ml)
Whole milk, 1/2 cup (120 ml)
Bay leaf, 1
Fine sea salt, 1 tsp (6 g)
Lemon juice, 1 tbsp (15 ml), plus more for the holding water
Freshly ground white pepper, to taste
For the hazelnuts
Piedmont hazelnuts, shelled, 3 1/2 oz (100 g)
Fine sea salt, 1 small pinch
For finishing
Heavy cream, cold, 3 tbsp (45 ml)
Hazelnut oil, 2 tsp (10 ml)
Chives, finely sliced, 1 tbsp
Flaky sea salt, to taste
Preparation
Scrubbing and cutting the topinambur
Scrub the tubers hard under cold water with a stiff brush and do not peel them. The skin is thin, carries much of the mineral flavour, and peeling a knobbly topinambur wastes a third of it. Cut them into rough 3/4 inch (2 cm) pieces and drop them into cold water with a squeeze of lemon, since cut flesh browns within minutes.
Washing and slicing the leeks
Trim the leeks to the white and palest green, split them lengthways and fan the layers under running water, because grit lodges deep in the shaft and one gritty spoonful ruins a smooth soup. Slice them into thin half moons, wash them again in a bowl and lift them out rather than draining, so the sand stays at the bottom.
Sweating the leeks pale
Melt the butter with the olive oil in a heavy pot over low heat, add the leeks with a pinch of salt and cover. Sweat them 10 to 12 minutes, stirring now and then, until completely soft and still white. No colour at all: even light browning gives a toasted note that reads as onion and buries the tuber, which is the flavour you are protecting.
Cooking the tubers in restrained stock
Drain the topinambur, add it to the pot with the potato and the bay leaf, and pour in just enough stock to sit level with the vegetables rather than cover them, about 3 cups (700 ml). Hold the rest back. Simmer 20 to 25 minutes until a knife goes through with no resistance, since undercooked topinambur stays faintly crunchy in the blender.
Toasting and skinning the hazelnuts
While the soup simmers, toast the hazelnuts at 325°F (165°C) for 10 to 12 minutes, until the skins crack and the kitchen smells sweet. Tip them hot into a clean towel, fold it over and rub firmly: most of the skins come away and the remaining flecks do no harm. Set aside 1 oz (30 g) of the best nuts for the garnish.
Building the hazelnut milk
Put the remaining hazelnuts in a blender with the warm milk and blend a full minute, until you have a thick pale liquid with no visible grit. This is what carries hazelnut through the whole bowl instead of leaving it on top as a garnish, and blending with liquid rather than alone stops the nuts turning into a butter that will not disperse.
Blending the soup in one burst
Remove the bay leaf. Blend the hot soup with the hazelnut milk on high for about 40 seconds, in batches if the jug is small, filling it no more than two thirds and holding the lid with a folded cloth. Stop as soon as it is smooth. The potato is the one ingredient that turns gluey under a blade, and it does so with time rather than speed.
Passing and correcting the consistency
Push the purée through a fine mesh sieve with a ladle, which takes two minutes and removes the last hazelnut fragments and tuber fibre. Judge the body in a clean pot: it should coat a spoon and fall in a ribbon, not a drip. Loosen with the reserved warm stock a little at a time, and leave it looser than you want, because inulin thickens as it cools.
Seasoning and holding for service
Season with salt and white pepper, then add the lemon juice off the heat and taste again. The acid is not there to be tasted; it lifts the sweetness of leek and tuber and stops the soup reading flat. Hold at around 160°F (70°C), covered, stirring occasionally. Do not let it boil once the hazelnut milk is in, or the emulsion breaks.
Plating
Warm the bowls well, because a vellutata this smooth has no crust or garnish to hold heat and will cool faster than a chunky soup. Wide shallow bowls with a deep centre are right: they give you a broad pale surface to work on and still pool the soup rather than spreading it thin.
Ladle about 1 cup (240 ml) into each bowl and let it settle flat. Crush the reserved hazelnuts coarsely with the flat of a knife, not in a grinder, so you get irregular pieces with some bite, and scatter a small heap slightly off centre rather than across the whole surface. A clean area of soup beside them is what makes the bowl look composed.
Whip the cold cream for a few seconds to a loose ribbon and drop a spoonful beside the nuts, then add three or four drops of hazelnut oil around it and a scattering of chives. The oil should sit as distinct beads on the surface, not be stirred in. Finish with flaky salt on the nuts alone and serve immediately, before the cream sinks.
Professional Technique
The technique that defines this soup is working with inulin instead of starch. Potatoes, squash and chestnuts store energy as starch, whose granules swell and gelatinise in hot water and thicken a soup as it simmers. Topinambur stores energy as inulin, a chain of fructose units that dissolves rather than gelatinising. Simmering a pot of pure topinambur therefore produces a thin liquid no matter how long you cook it, and the body has to be created another way.
That way is mechanical. Inulin in solution behaves like a soluble fibre gel, and blending shears the cooked tuber fibre fine enough to hold it in suspension, which is where the velvet comes from. It also means the soup thickens noticeably as it cools, since inulin sets slightly below serving temperature, and that an overly thick purée cannot be thinned convincingly with more blending. Judge the consistency hot, leave it looser than looks right, and correct with stock rather than time.
The small quantity of potato is a deliberate compromise and the one place this recipe can go wrong on technique. Potato brings the rounded mouthfeel that pure topinambur lacks, but its starch granules rupture under a high speed blade and release amylose that turns a purée to wallpaper paste. Cutting it small so it cooks through, keeping it to a fifth of the tuber weight, and blending in one short burst rather than a long run are what keep it useful instead of ruinous.
Texture and Moisture Control
Liquid discipline decides everything here. Adding all the stock at the start is the commonest way to end up with a pale thin soup that no amount of reduction will fix, because reducing it also concentrates the salt and dulls the tuber. Cook with the liquid level with the vegetables, blend at that density, then open the purée up with warm stock a spoonful at a time until it ribbons off the spoon.
Temperature governs both texture and flavour. Serve at around 150°F (65°C), hot enough to smell of hazelnut but not so hot that the volatile sweetness of the leek is driven off. Held much hotter the soup tightens and a skin forms; held at a simmer with cream and hazelnut milk in it, the fat separates and beads on the surface. Keep it covered off direct heat and stir it every few minutes.
The sieve is the last control and the one most home cooks skip. Even a powerful blender leaves hazelnut particles and tuber fibre that the tongue reads as grain, and no extra blending removes them. Two minutes with a fine mesh sieve and a ladle turns the same ingredients into something that coats the palate evenly, and it costs nothing in flavour or volume.
Professional Mise en Place
The whole soup can be finished ahead except the garnish, which is the opposite of most primi. Plan around holding the purée correctly rather than around speed.
Equipment and tools
High speed blender and a fine mesh conical sieve
Heavy bottomed pot with a lid, wide enough to sweat leeks in one layer
Stiff vegetable brush, small tray for toasting, clean towel for skinning
Ladle, warmed bowls, small spoon or dropper for the hazelnut oil
Prepared ahead
Topinambur scrubbed and cut, held in acidulated water, up to 4 hours
Leeks washed and sliced, kept covered and cold
Hazelnuts toasted and skinned, up to 2 days ahead in a sealed jar
Soup blended and sieved, up to 2 days ahead and refrigerated
Service setup
Purée held at 160°F (70°C), covered, with warm stock beside it for slackening
Reserved hazelnuts crushed at the last moment so they stay crisp
Cream whipped loose and kept cold, chives sliced and dry
Bowls warming, hazelnut oil and flaky salt within reach
Chef Tips
Choose tubers that are firm and heavy with tight skin, and prefer the smoothest shapes. Knobbly ones taste the same but hold soil in every crevice. Leave behind any that give under thumb pressure or show soft brown patches, because that softness is the start of fermentation and tastes of it.
Inulin is not digested in the small intestine, which is why topinambur has a reputation for causing wind. Thorough cooking and a sensible portion largely solve it, as does serving the soup as a first course rather than a bowlful on its own.
Taste a hazelnut before you toast the batch. Nuts that have sat warm in a shop for months are already rancid, and once that flavour is blended through the soup it cannot be removed. Buy Piedmont hazelnuts from somewhere with real turnover and toast them the same day.
For a vegan version, drop the butter and cream and blend the hazelnuts with hot water instead of milk. The result is leaner and more clearly nutty, and a few extra drops of hazelnut oil replace the richness the cream provided.
Common Mistakes
Peeling the topinambur. The skin is thin, edible and carries much of the earthy mineral character, and peeling a knobbly tuber can lose a third of its weight. Scrub it hard with a brush instead, and cut away only bruises and the dry stem end.
Browning the leeks. Any colour on the leek turns into a caramelised onion note that dominates the finished bowl and hides the tuber entirely. Sweat covered over low heat with a pinch of salt and check that the slices stay white throughout.
Drowning the vegetables in stock. Stock added to cover produces a thin soup that cannot be recovered, since reducing it concentrates salt faster than flavour. Cook with the liquid level with the vegetables and open the purée out afterwards, which you can always do and cannot undo.
Running the blender too long. The potato is the risk, not the topinambur. Extended blending ruptures its starch granules and turns a silky purée gummy and sticky in the mouth. Forty seconds on high is enough, and the sieve deals with whatever is left.
Boiling the soup after the hazelnut milk goes in. Nut and dairy fat holds in suspension only below a simmer, and a boil breaks it into an oily film that will not stir back together. Hold the soup at 160°F (70°C) covered, and reheat gently for the same reason.
Wine Pairing
Gavi DOCG: Cortese from the south east corner of Piedmont, and the regional white that fits this bowl most cleanly. Its taut green apple acidity cuts hazelnut fat without stripping it, while a faintly saline, chalky finish echoes the mineral edge of the tuber. Serve it near 50°F (10°C).
Alta Langa DOCG: Piedmont's traditional method sparkling, from Pinot Nero and Chardonnay grown on the same hills as the hazelnuts. Long ageing on the lees gives a bread and toasted nut character that runs alongside the garnish, and the bubble lifts a dense purée off the palate between spoonfuls.
Verdicchio di Matelica DOC: A step outside Piedmont, into the cooler inland valley of the Marche, and worth it for the structure. Matelica Verdicchio is firmer and more mineral than its coastal cousin, with white flowers, anise and a bitter almond finish that picks up the toasted hazelnut instead of being smothered by the cream.
Offida Pecorino DOCG: For anyone who finds lighter whites vanish against a thick soup. Pecorino has real weight and a waxy texture, with ripe pear and a herbal note behind it, and enough acidity to stay fresh at that body. It sits underneath the vellutata rather than beside it.
Alto Adige DOC Pinot Nero: The red option, and a light one. Alpine Pinot Nero keeps sour cherry fruit, low tannin and a forest floor note that meets the earthiness of the topinambur head on. Serve it cool, near 57°F (14°C), and unoaked, since vanilla would flatten the delicacy of the leek.
Storage & Reheating
The purée keeps refrigerated in an airtight container for up to 3 days and improves slightly on the second, once the hazelnut has settled through it. Cool it quickly in a shallow tray rather than leaving the pot on the stove, and refrigerate it without the garnishes. Expect it to set noticeably firm when cold, which is the inulin and not a fault.
Reheat gently in a saucepan over low heat, stirring, and slacken with warm stock or water until it ribbons again. Never bring it back to a boil, which splits the nut and dairy fat out of suspension and leaves an oily film. If it has separated slightly in the refrigerator, a few seconds with a stick blender off the heat brings it back together.
It freezes for up to 1 month, best done before the cream is anywhere near it. Freeze in portions, thaw overnight in the refrigerator and expect some separation on thawing, which a short blend corrects. Toasted hazelnuts keep 2 weeks in a sealed jar at room temperature and should be crushed only at the moment of serving, since crushed nuts go soft and stale within hours.
Nutrition
Per serving, based on 4 servings with the cream and hazelnut garnish:
Calories: 415 kcal
Total Fat: 28 g
Saturated Fat: 8 g
Trans Fat: 0.3 g
Unsaturated Fat: 19 g
Cholesterol: 30 mg
Sodium: 590 mg
Total Carbohydrates: 33 g
Fiber: 5 g
Total Sugars: 12 g
Added Sugars: 0 g
Protein: 8 g
Lactose: 1.8 g
Principal micronutrients: potassium, iron, thiamine, vitamin E, magnesium, copper, manganese
These figures are estimates. Most of the carbohydrate in topinambur is inulin, which is largely not absorbed, so the usable energy is lower than the carbohydrate figure suggests, and the sodium depends on how the stock was salted.
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