Soupe aux Grenouilles de la Meuse

Ingredients

• 800 g frog's legs, cleaned and paired (cuisses de grenouilles)
• 500 ml cold whole milk, for soaking
• For the velouté base
• 1 medium onion, finely diced
• 1 leek, white part only, finely diced
• 2 stalks celery, finely diced
• 40 g unsalted butter
• 15 g plain flour, approximately 1 tablespoon
• 750 ml chicken stock, good quality, unsalted
• 200 ml dry Riesling, one glass
• For the frog's legs
• 30 g unsalted butter, for sautéing
• 1 garlic clove, minced
• For the liaison
• 150 ml crème fraîche
• 2 egg yolks
• To finish
• 1 small bunch flat-leaf parsley, generous chiffonade
• 4 slices day-old white bread, cut into small cubes for croutons
• 30 g unsalted butter, for frying croutons, with a garlic clove
• 1 garlic clove, for crouton butter

Method

1. 1
   Place the frog's legs in a bowl and cover entirely with cold milk. Leave to soak for 1 hour. The flesh whitens and any residual marshy scent dissipates. Drain and pat dry with kitchen paper before proceeding.
2. 2
   Melt 40 g butter in a wide saucepan over low heat. Add the diced onion, leek white, and celery. Sweat gently, stirring occasionally, until the vegetables are soft and translucent but have taken no colour whatsoever — 8 to 10 minutes. The butter should remain pale gold.
3. 3
   Stir in the flour and cook for 1 to 2 minutes, keeping the heat low, to form a white roux. Add the Riesling gradually, whisking constantly, then pour in the chicken stock in a steady stream, whisking to produce a smooth, lump-free velouté. Raise the heat to a gentle simmer and cook uncovered for 20 minutes.
4. 4
   While the soup simmers, melt 30 g butter in a frying pan until it foams. Add the minced garlic clove and, immediately, the dried frog's legs. Sauté for 2 minutes per side over medium heat. This is where the dish lives or dies: the legs must be removed the moment they feel just firm to a gentle press of the finger — a second beyond that and the flesh turns rubbery and cannot be recovered.
5. 5
   Pick the meat from the bones over a clean board. Each leg yields two small morsels of pearl-white flesh; reserve these covered. Add the stripped bones to the simmering soup and cook for a further 10 minutes. The stock deepens in sweetness and body.
6. 6
   Strain the soup through a fine sieve into a clean pot, pressing the solids to extract all liquid. Discard the solids. The resulting velouté should be smooth and pale ivory in colour.
7. 7
   In a bowl, whisk together the crème fraîche and 2 egg yolks. Ladle a little of the hot soup into the liaison, whisk to temper, then pour back into the pot, stirring to combine. Return to the lowest possible heat. The soup must not boil from this point: bring only to a gentle warmth sufficient to heat through. A boil will curdle the liaison irreparably.
8. 8
   Add the reserved frog meat and the parsley chiffonade to the soup off or barely on the heat. Stir once to distribute. The soup is ready when the meat is warmed through but has not contracted further — test a morsel; it should yield softly between the teeth, tasting of clean cream, faint garlic, and gentle sweetness.
9. 9
   Fry the bread cubes in butter with a bruised garlic clove until golden and crisp on all sides. Drain on paper. Ladle the soup into warm bowls, scatter croutons over the surface, and serve at once.