Sauce Vin Blanc — White Wine Fish Sauce

Ingredients

• 4 fillets (approx. 160 g each) sole, turbot, brill, or firm white fish fillets, skin removed
• 2 shallots, finely minced
• 150 ml dry white wine, unoaked; enough with fumet to come halfway up fillets
• 150 ml fish fumet, equal part to white wine
• 250 ml fish velouté, prepared ahead
• 100 ml heavy cream
• 40 g unsalted butter, cold, cut into cubes, for mounting
• For the beurre manié
• 15 g plain flour, kneaded with butter to a paste
• 15 g unsalted butter, soft, kneaded with flour to a paste
• 1 sheet parchment paper, buttered, cut to fit pan (cartouche)
• to season fine salt

Method

1. 1
   Heat the oven to 180 °C. Butter a sautoir or shallow flameproof pan. Scatter the minced shallots evenly across the bottom. Lay the fish fillets on top in a single layer. Pour over the white wine and fish fumet in equal parts until the liquid comes halfway up the fillets — no higher. Season with salt. Lay the buttered cartouche directly on the fish, bring to a bare simmer on the stovetop, then transfer to the oven. Poach for 8–12 minutes depending on thickness. The fish is done when it yields to the lightest pressure and is opaque through to the centre.
2. 2
   Lift the fillets carefully onto a warm plate. Cover them with the cartouche and keep warm. Pour the cooking liquid through a fine sieve into a small saucepan. Whisk in the beurre manié (flour and butter kneaded to a paste) to give the liquid immediate body. Set over high heat and reduce by two-thirds — you are aiming for approximately 150 ml of intensely flavoured liquid. This step is where the dish lives or dies: the reduction must be rapid and over high heat; slow reduction over moderate heat darkens the sauce and drives bitter, concentrated notes into it. The liquid is ready when it is glossy, syrupy at the edges of the pan, and smells sharply and cleanly of fish, shallot, and wine.
3. 3
   Reserve 2 tablespoons of the concentrated reduction and set aside. Pour the remainder into the 250 ml of fish velouté in a clean saucepan. Reduce the combined sauce over medium heat, stirring, until it coats the back of a spoon and holds a clean line when a finger is drawn across it.
4. 4
   Remove the pan from the heat. Add the cream, then swirl in the cold butter cube by cube until the sauce is fully emulsified, pale gold, and glossy. Stir in the reserved 2 tablespoons of concentrated reduction. Adjust seasoning. The sauce should taste first and foremost of the fish it accompanied, with wine providing brightness and butter providing richness — not of cream or of any single element in isolation.
5. 5
   Arrange the fillets on warmed plates. Nap each portion with sauce, ensuring an even, glossy coat. Serve immediately — the fish must not be allowed to release further liquid back into the sauce.