Filets de Soles Walewska

Ingredients

Equipment Needed

• •12-inch wide lidded skillet
• •Two medium heavy-bottomed saucepans
• •Fine-mesh sieve
• •Whisk
• •Fish slice or wide flexible spatula
• •Shallow 2-quart broiler-safe gratin dish
• •Kitchen shears or sturdy wooden spoon for crushing shells

Instructions

1. 1

   Prepare the fish

   Shell the langoustines, keeping every head and shell for the butter. Split each tail lengthwise and remove the dark intestinal thread, giving you 24 half-tails. Cut the raw truffle into 24 fine slices. Pat the sole fillets dry, season them lightly with half the salt and the white pepper, and keep the fish and tails cold while you build the sauces. Butter a shallow 2-quart broiler-safe gratin dish.

2. 2

   Extract langoustine butter

   Crush the reserved langoustine heads and shells roughly in a medium saucepan, then add the 6 tablespoons of butter. Cook over medium-low heat for 10 to 12 minutes, pressing and turning the shells often, until the butter is coral-colored and smells intensely of sweet shellfish. Keep the heat below browning; scorched milk solids will make the whole sauce bitter. Strain through a fine sieve, pressing firmly to recover every drop. Measure 3 tablespoons (45 ml / 42 g) for the sauce and reserve any excess for another fish dish.

3. 3

   Build delicate Mornay

   Melt the 3 tablespoons of butter in a clean saucepan over medium-low heat. Stir in the flour and cook for 2 minutes without letting the roux color; this sauce should remain ivory. Whisk in the milk gradually, then the cream, and hold the sauce at a bare simmer for 5 to 7 minutes, whisking until it is nappé, thick enough to coat the back of a spoon. Remove it from the heat and stir in the Gruyère, Parmesan, nutmeg, and a little of the remaining salt. If lumps appear, whisk vigorously off the heat or pass the sauce through the fine sieve. Cover its surface directly and keep it warm, never boiling.

4. 4

   Poach the sole

   Warm the fish fumet in a wide lidded skillet until its surface barely trembles. Lay in the sole fillets flat and in their natural shape, without folding or rolling them, working in two batches if the pan cannot hold them in one layer. Cover and poach over the gentlest heat for 3 to 5 minutes, until the edges are opaque and the centers retain the faintest translucence. Lift the fillets carefully with a fish slice, let them drain, and arrange two per serving in the buttered gratin dish. Reserve the poaching fumet. Pale and delicate is correct here; the broiler still has work to do.

5. 5

   Stew the garnish

   Heat the broiler fully, with a rack about 5 inches beneath it. Melt the 2 tablespoons of butter in the wiped skillet over medium-low heat. Add the split langoustine tails, truffle slices, and a pinch of the remaining salt, then cover and cook for about 90 seconds. Turn the tails, cover again, and cook for 30 to 60 seconds more, just until their flesh turns pearly and barely opaque. Take them off the heat immediately. Surround each pair of sole fillets with six half-tails and six truffle slices, spooning over the fragrant butter from the pan.

6. 6

   Finish with shellfish butter

   Return the Mornay to very low heat and whisk in 1 to 3 tablespoons of the reserved poaching fumet, only enough to restore a soft coating consistency. Remove the pan from the heat. Whisk in the measured langoustine butter a spoonful at a time until the sauce is glossy, coral-ivory, and tastes unmistakably of shellfish. Do not boil it now. If the butter separates and an oily rim appears, stop. Ça se rattrape: put 1 teaspoon of warm fumet in a clean warm bowl, whisk in a spoonful of the broken sauce until smooth, then add the rest gradually, whisking after every spoonful.

7. 7

   Glaze and serve

   Coat the sole, langoustines, and truffle completely with the hot Mornay. Slide the dish beneath the fully heated broiler for 60 to 120 seconds, watching without interruption, until the sauce bubbles at the rim and takes small golden freckles across the surface. If the broiler colors unevenly, rotate the dish rather than leaving the sole beneath the heat for several more minutes. Bring it straight to the table while the sauce still gleams. À table!

Chef Tips

• •Buy raw, shell-on langoustines, fresh or carefully thawed. Precooked tails cannot survive the butter stew and broiler, and bare tails leave you nothing from which to extract the langoustine butter. Here the shells are part of the sauce.
• •The source enriches each pint of Mornay with one and one-half ounces of langoustine butter. Three tablespoons (45 ml / 42 g) in this roughly 2-cup batch preserves that proportion at a four-person table. This is not brigade scaffolding. It is the flavor that decides the dish.
• •True Dover sole has the fine grain and flexibility the dish expects. Lemon sole or thin flounder fillets will accept the same method, but they are more fragile and may poach a minute sooner; lift them before they begin to flake apart.
• •This dish truly needs fresh raw truffle. Preserved slices bring little perfume and often carry enough liquid to thin the sauce. If fresh truffle is unavailable, choose another sole preparation rather than asking a jar to impersonate it.
• •Serve with something quiet, such as buttered spinach or small boiled potatoes. Pour Champagne or a poised white Burgundy with enough freshness to cut through the Mornay; the plate already has all the ornament it needs.

Advance Preparation

• •The langoustine butter can be extracted up to 2 days ahead, covered, and chilled. Let it soften before whisking it into the warm Mornay.
• •The Mornay can be prepared earlier the same day. Press parchment directly against its surface, chill promptly, then reheat over very low heat with a spoonful of milk. Add the langoustine butter only during the final assembly.
• •The sole can be trimmed and the langoustine tails shelled up to 4 hours ahead and kept covered in the cold. Slice the truffle shortly before cooking so its perfume stays on the plate rather than the cutting board.
• •Do not assemble or glaze the dish in advance. Once the sole is poached, the final steps should move without pause so the fish stays tender and the sauce keeps its gloss.

Frequently Asked Questions

Nutrition Information

1 serving (about 375g)