1 Preheat the oven to 550 degrees. Put the fumet in a medium saucepan over high heat. Bring to a boil, lower the heat, and simmer until reduced to ¼ cup, about 3 minutes.

2 Put 8 tablespoons of butter in a medium saucepan over high heat. Cook, gently shaking the pan, until the butter turns dark brown, but not black, about 2 minutes. Pour the vinegar into the center of the pan and whisk it in. Remove the pan from the heat and continue whisking for about 20 seconds.

3 Bring the fish fumet to a boil and, whisking constantly, begin very slowly dripping in the brown butter. After about 15 seconds, pull the pan off the heat but keep it near the hot burner. Continue slowly adding the butter until the sauce is emulsified and all the brown butter is incorporated. Add the remaining 2 tablespoons of butter and whisk slowly until it is absorbed into the sauce. Stir in the capers and season with pepper. Cover and keep warm, near but off of the heat.

4 In a pot, bring the court bouillon to a boil. Season the skate on both sides with salt and pepper and place it in the roasting pan (the pieces may over—lap slightly). Pour the court bouillon over the skate, place in the oven, and cook until a knife can be easily inserted between the creases in the fish, about 3 minutes.

5 Use a long, wide spatula to transfer the skate to 4 dinner plates. Spoon the sauce over and around the skate, to completely cover the plate; make sure the capers are evenly distributed over the fish. Sprinkle the chives over the skate and sauce and serve immediately.