Crab-Stuffed Sole Paupiettes with Sauce Vin Blanc

1. 1Melt the butter in a medium frying pan over medium heat until foaming. Add the shallot and cook, stirring occasionally, until softened but not browned, about 3 to 4 minutes.
2. 2Sprinkle in the flour, stir to coat the shallot, and cook until the raw taste has cooked off, about 1 minute. Whisk in the wine and simmer until the mixture has reduced slightly and thickened, about 1 to 2 minutes.
3. 3Whisking constantly, slowly pour in the cream and bring to a simmer. Continue simmering until the sauce has thickened and reduced by about a third, about 8 minutes.
4. 4Remove the pan from the heat and stir in the crabmeat, chives, lemon zest, lemon juice, salt, and pepper until combined (the mixture should be thick). Transfer to a large plate and spread into an even layer. Cover loosely with plastic wrap and refrigerate until completely chilled, about 1 to 1 1/2 hours.

For the fish and the sauce:

1. 1Heat the oven to 200°F and arrange a rack in the middle.
2. 2Place a fine-mesh strainer over a medium heatproof bowl and set aside.
3. 3Combine the water, wine, shallots, carrots, celery, parsley, and measured salt in a large straight-sided frying pan with a tightfitting lid and bring to a boil over high heat. Reduce the heat to medium and simmer until the poaching liquid has reduced by a third and the flavors have developed, about 20 minutes.
4. 4Meanwhile, place the sole fillets in a single layer on a work surface and lightly season both sides with salt and white pepper. Divide the chilled crab filling among the fish fillets, spreading it into a thin, even layer along the length of each fillet and leaving a 1/4-inch border. Starting with the thicker end, roll up each fillet. Place the fillet rolls seam-side down in a shallow baking dish, cover the dish with plastic wrap, and refrigerate.
5. 5Pour the poaching liquid through the reserved strainer and discard the contents of the strainer. Return the poaching liquid to the pan, bring it to a bare simmer over high heat, then reduce the heat to low. Reserve the strainer and medium heatproof bowl for later use.
6. 6Place the rolled fillets seam-side down in the poaching liquid and cover the pan. Poach at a low simmer until the fish is opaque and firm to the touch, about 18 to 20 minutes. Meanwhile, wash and dry the shallow baking dish and set it aside.
7. 7Using a flat spatula, carefully transfer the fish to the clean baking dish. Pour the poaching liquid through the strainer and discard the contents of the strainer. Pour 1/2 cup of the strained liquid into the baking dish. Cover with aluminum foil and place in the oven to keep warm. Line a plate with paper towels; set aside.
8. 8Pour 1 cup of the strained poaching liquid into a small saucepan and bring to a boil over medium-high heat. (If you have less than 1 cup of poaching liquid left, add enough water to make 1 cup.) Boil until the liquid is reduced to 3/4 cup, about 4 minutes. Meanwhile, mix the butter and flour together in a small bowl until a smooth paste has formed; set aside.
9. 9Reduce the heat under the poaching liquid to medium. While whisking, slowly add the cream and then simmer, whisking occasionally, until the sauce coats the back of a spoon and has reduced to 1 cup, about 3 minutes.
10. 10Whisk in the butter-flour mixture and simmer, stirring constantly, until the butter mixture is incorporated and the sauce has thickened, about 1 to 2 minutes.
11. 11Remove the pan from the heat and stir in the lemon juice. Taste the sauce and season with salt and pepper as needed.
12. 12To serve, spoon 2 tablespoons of the sauce onto a small plate. Place one paupiette on the towel-lined plate to remove the excess moisture, then place in the sauce. Repeat with the remaining paupiettes. Evenly drizzle the remaining sauce over the paupiettes and garnish each with 2 crossed pieces of chive. Serve immediately.