Filets de Soles Olga, otherwise “Otero”

Ingredients

Equipment Needed

• •Rimmed baking sheet
• •Shallow 9-by-13-inch (23-by-33-cm) baking dish
• •Two 1-quart (1-liter) heavy saucepans
• •Small whisk
• •Flexible fish spatula
• •Small spoon or melon baller
• •Instant-read thermometer

Instructions

1. 1

   Bake the potato shells

   Heat the oven to 425°F (220°C). Prick the potatoes in several places and bake them directly on a rimmed sheet for 50 to 60 minutes, until a skewer enters without resistance but the skins remain firm. Cut a long strip, about 1 inch (2.5 cm) wide, from the top of each potato. While they're still hot, scoop out the pulp carefully, leaving an even ¼-inch (6 mm) wall and an intact shell. Season the interiors lightly, then return them cut-side up to the oven for 6 to 8 minutes, until the inner surface looks dry and faintly chalky. Save the pulp for another meal; it does not return to this dish.

   If a shell tears, don't discard it. Set it snugly in a small ovenproof ramekin before filling, which supports the split without changing what goes inside.
2. 2

   Make the Mornay

   While the potatoes bake, melt 2 tablespoons (30 ml / 28 g) of the butter in a small heavy saucepan. Stir in 2 tablespoons (30 ml / 16 g) of the flour and cook this pale roux for 2 minutes without letting it color. Whisk in the milk gradually, followed by ¼ cup (60 ml / 60 g) of the cream. Simmer gently for 5 to 7 minutes, whisking, until the sauce is smooth and coats the back of a spoon. Remove it from the heat and stir in ½ cup (120 ml / 50 g) of the Gruyère and all the Parmesan. Season lightly with salt and white pepper, then cover the surface directly and keep warm. If the Mornay turns oily after the cheese goes in, take it off the heat and whisk in 1 tablespoon (15 ml / 15 g) of the reserved cold cream. Ça se rattrape.

3. 3

   Poach the sole

   Lower the oven to 350°F (180°C). Use 1 teaspoon (5 ml / 5 g) of the remaining butter to coat a shallow baking dish. Fold each sole fillet into a compact packet by bringing the thin tail inward and folding the thicker end over it, then arrange the packets in one layer. Season with salt and white pepper. Pour ¾ cup (180 ml / 180 g) of the fumet around the fish, reserving the rest, and cover closely with parchment or foil. Poach in the oven for 7 to 10 minutes, until the edges are opaque but the centers remain faintly pearly, about 135°F (57°C). The sole will finish beneath the glaze. Lift the fillets carefully to a warm plate and strain the poaching liquid into a clean saucepan.

4. 4

   Bind the shrimp

   Add the white wine to the strained poaching liquid and boil briskly until reduced to about ⅓ cup (80 ml). Make a beurre manié, flour kneaded with butter, from the remaining 2 teaspoons (10 ml / 10 g) butter and 2 teaspoons (10 ml / 5 g) flour. Whisk the beurre manié into the reduction a little at a time, then simmer for 2 minutes to cook out the flour. Add the remaining cream and simmer gently until the white-wine sauce lightly naps the spoon. If it's too thick, loosen it with reserved fumet; if it's thin, reduce it before adding the shrimp. Fold in the shrimp just long enough to warm them. They should be cohered by sauce, not swimming in it.

5. 5

   Fill the shells

   Set the dried potato shells on a broiler-safe rimmed sheet. Divide the shrimp evenly among them, placing one tablespoonful in the bottom of each shell with just enough white-wine sauce to bind it. Set one folded sole fillet over each shrimp layer. If the Mornay has tightened while standing, whisk in a spoonful of warm fumet or milk, then cover every fillet completely and fill each shell neatly to its rim. Sprinkle with the remaining ¼ cup (60 ml / 25 g) Gruyère.

6. 6

   Glaze and serve

   Heat the broiler to high and place the sheet about 6 inches (15 cm) below it. Glaze the filled shells for 2 to 4 minutes, watching without distraction, until the Mornay bubbles at the edges and the cheese takes an even bronze. Everything underneath is already cooked, so color is the only purpose. If the top darkens before the sauce bubbles, lower the sheet by one rack and let the gentler heat finish the center. Confirm that the sole reaches 145°F (63°C), then transfer the shells to a warm platter and serve immediately. A cloth napkin beneath them belongs to brigade service; the warm platter keeps dinner simpler and the shells crisper. À table!

Chef Tips

• •Choose long, floury russet potatoes with unbroken skins and roughly matching widths. Waxy potatoes hold moist flesh against the shell, while a floury potato leaves the parched case this dish requires.
• •The potato pulp is deliberately removed, not folded into the filling. Save it for purée, croquettes, or a potage, but don't put it beneath the shrimp. The hollow shell is the vessel, and changing that changes the dish.
• •True sole is splendid here, but lemon sole, petrale sole, or another thin, firm flatfish fillet can carry the method honestly. Keep the pieces close to 3½ ounces (100 g) so they fold and poach at the same rate.
• •Use a clean, delicate fish fumet. If your best option is packaged fish stock, reduce it by one-third before measuring, then taste for salt. A strongly smoky stock or an assertive shellfish broth overwhelms the sole.
• •Serve with a mineral dry white wine, such as Chablis or another restrained white Burgundy. The plate already has cream, cheese, shrimp, fish, and potato; the glass should bring freshness, not another layer of weight.

Advance Preparation

• •Bake, hollow, and dry the potato shells up to one day ahead. Cool them completely, refrigerate uncovered until cold, then cover lightly. Reheat cut-side up at 350°F (180°C) for 8 minutes before filling so their interiors become dry again.
• •The Mornay can be made one day ahead. Press parchment directly against its surface, chill promptly, and reheat over very low heat with 1 to 2 tablespoons (15 to 30 ml / 15 to 30 g) milk. Don't let it boil once the cheese is in.
• •Drain and dry the shrimp earlier in the day, but poach the sole and make the white-wine sauce close to serving. Once assembled, the shells should go directly beneath the broiler and then to the table.

Frequently Asked Questions

Nutrition Information

1 serving (about 425g)