VichyssoiseVichyssoise
Leeks and starchy potatoes, cooked until the potatoes fall apart, puréed to a pale, fine silk, then chilled until it holds on the spoon. The only thing in the French set that is served cold, and the one where the potato does the work: its starch is what thickens the soup, and the cream just makes it smoother.
Technique notes
Vichyssoise is a puréed soup, and the one thing to get right is the order: the leeks cook first without colour, because a browned leek is a bitter leek; the potatoes cook until they fall apart at the touch of a fork; and then the whole thing breaks down into the body of the soup, because it is the starch in the potato, thickened in the liquid, that makes it hold, not the cream and not the butter. The cream goes in at the end, off the heat, only to make it smoother, and the chill is what takes it from a thick soup to a held one: the starch sets as it cools, and a vichyssoise served hot, without the chill, is simply an early version of a vichy. Cut the leeks into thin rings, and cook them low and slow, and the soup is as smooth as the liquid it is made from.
Equipment
- A heavy, wide soup pot, with a lid, for the long, low cook
- An immersion blender, or a blender and a fine sieve if you do not have one
- A fine sieve or tamis, to pull the soup through if it comes out grainy
- Wide, shallow bowls, for the serving
Ingredients
- 5 leeks, the white and first pale-green parts only, cut into 5 mm (¼-inch) rings, and washed well under cold water to draw the grit from the layers — a leek that is not rinsed is a soup that is gritty
- 600 g (about 1½ lb) starchy white potatoes — Yukon Gold or a firm new one, not a floury baking potato — scrubbed or thinly peeled, cut into 1 cm (½-inch) pieces
- 4 tbsp (60 g) unsalted butter
- 750 ml (3 cups) light chicken stock, or a good vegetable one if you are cooking it without meat
- 1 small thyme sprig, optional, for the simmer
- 200 ml (¾ cup) single (light) cream
- 1½ tsp (8 g) fine salt, plus more to taste
- A small pinch of freshly ground white pepper
- A drizzle of good olive oil, or a few chives, to finish, optional
Method
- Soft the leeks, no colour. Into the pot, over a low-medium heat, put the 4 tbsp of butter, and once it is melted add the leek rings, ½ tsp of the salt, and the thyme if you are using it. Let them cook, stirring now and again, for about 8–10 min, until they are soft, pale, and their sharpness is gone. The moment they go gold, they are going the wrong way — the leek here is the quiet, green note, not a brown one.
- Add the potatoes, and let them collapse. Stir in the cut potatoes, pour in the stock, and bring it to a simmer. Once it is simmering, lower the heat to a gentle one, and let it cook for about 15–20 min, until the potatoes are fully cooked and go soft under a fork. The liquid should be down to about 600 ml (2½ cups): the soup thickens on its own, and the potatoes are doing that work.
- Pull the thyme, and purée it fine. Take out the thyme sprig. Blend the soup — with the immersion blender, or in a blender in batches — for a 1–2 min, until it is fine and silky, with no rough piece of potato left in it. If it is still the least bit grainy, pull it through a fine sieve back into the pot: the whole point is a surface you can see through, not around.
- Whisk in the cream, off the heat. Take the pot off the heat, and whisk in the 200 ml of cream and the rest of the salt and a pinch of white pepper. The cream goes in off the heat so it stays smooth, and the soup at this point is a pale, thick, still-warm liquid that is going to hold differently once it is cold.
- Cool it, and let the starch set. Let the soup come to room temperature, then cover it and put it in the fridge for at least 2 hr, or overnight if it fits around the rest. The chill is doing real work: the potato starch thickens as it cools, and the soup goes from loose to the point where it holds on the back of a spoon. If it ends up too thick, loosen it with a little warm stock; too thin, and the fix is to reduce it again gently before it goes back in.
- Serve it cold, wide and shallow. Taste it once cold — a vichyssoise always wants a little more salt than it did hot — stir it loose, and serve it in a wide shallow bowl with a thin drizzle of the cream, the chives if you have them, and the oil if you are using it. It is a starter, and it sits for as long as the table needs, so make it early and let it rest.
Common failures
- The soup is thin and watery, and will not hold. There is too much liquid for the potato, or the potatoes did not break down. Cut back to the 600 g of starchy potato, and cook them until they are really falling apart before you blend: the starch is the whole thickness, and a soup that is thin at the end was thin because the starch is missing.
- A raw, sharp leek note. The leeks were undercooked. They are the thing that is cooked first, and they need the full 8–10 min in the butter until their sharpness is gone — a vichyssoise that tastes of raw leek is a leek that did not finish its cook.
- A grainy, lumpy texture. The blend was too short, or the potato is too big. Blend longer, and then sieve anyway, because the difference between a grainy and a silky vichyssoise is the last 30 sec of the blender and the pass through the sieve.
- The cream has curdled into little flakes. It went in over too hot a pot. Add the cream with the heat off; a vichyssoise wants a cold finish, and the cream in particular does not do well under a rolling boil.
Variations & substitutions
- The hot version — a vichy. Cook the same soup, and serve it hot instead of chilled, with the cream and the salt in at the end. It is the same leek-and-potato, served warm: a quiet, buttery hot soup in place of a cold one.
- Half potato, half cauliflower. Swap half of the potato for the same weight of cauliflower florets, and let them do the same work. It is a little lighter, and a little closer to a cream, and the leek stays the same.
- A moreish version. Before you purée, fry 100 g of good bacon or smoked ham in the butter, and let the fat and the smoke go into the leeks as they cook. The rest of the dish is what it always is; this one just has a little more at the back of it.
What to serve with it
A vichyssoise sits as a cold starter in front of anything, and it does not want much: the quiche, or the tatin, or a little plate of cold meat, and the cold soup carries the whole table. On its own it is a bowl that is served as long as the table can hold, and the thing that belongs in it is a crisp — a piece of well buttered baguette, cut thin and crisped in the oven, for the one thing in the table that is not in a bowl.
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