Velouté de Champignons — Cream of Mushroom Soup

Velouté de champignons demonstrates the classical velouté-based soup method — a roux-thickened stock enriched with mushroom essence and finished with a liaison of egg yolks and cream to produce a soup of extraordinary silkiness and concentrated fungal depth. Unlike the simpler puréed potages, a velouté soup builds upon the mother sauce technique, requiring a blonde roux, quality stock, and the crucial liaison finish that defines the velouté family. Begin by preparing a mushroom essence: sweat 400g of finely sliced button or Paris mushrooms in 40g of butter with a squeeze of lemon juice (to prevent oxidation) over medium heat for 10-12 minutes until they release all moisture and it evaporates completely. This duxelles-like concentration intensifies mushroom flavour threefold. Set aside a quarter for garnish. In a separate pot, make a blonde roux with 40g of butter and 40g of flour, cooking for 3-4 minutes until the mixture smells biscuity and has turned pale gold. Gradually whisk in 1 litre of chicken stock, bring to a gentle simmer while whisking, then add the sweated mushrooms. Simmer for 30 minutes, skimming any impurities that rise. Purée until smooth and pass through a fine sieve. Return to gentle heat and prepare the liaison: whisk 2 egg yolks with 100ml of double cream. Temper the liaison by whisking a ladleful of hot soup into the yolk mixture, then pour this back into the pot, stirring constantly. Heat gently — the soup must not boil after the liaison is added, or the yolks will scramble, producing an irreversible curdled texture. The temperature should reach 82-84°C: hot enough to thicken, cool enough to prevent coagulation. Finish with 30g of cold butter, season with salt, white pepper, and a grating of nutmeg. Garnish with the reserved sautéed mushroom slices and a drizzle of truffle oil for luxury. The soup should be the colour of pale stone, thick enough to coat a spoon, and carry the deep, earthy perfume of concentrated mushrooms.