Skate with black butter
To clarify the butter, melt in a pan over a low heat without stirring. Remove from the heat and cool slightly. Skim off the foamy mixture from the surface. Pour off the clear yellow liquid and reserve. Discard the milky sediment left in the pan.
Pat the skate dry with kitchen paper. Cut fillets from either side of the cartilage using a sharp knife, cutting close to the cartilage. Place skin side down on a chopping board and, using a sawing motion, cut along the length of the wing. Cut into similar-sized pieces.
Put the stock and vinegar in a large heavy pan, and bring to the boil. Add the skate and poach for 8 minutes. Drain well and pat dry with kitchen paper.
Melt a little butter in a frying pan, and cook the skate for 1–2 minutes on each side until tender. Put on a serving dish and keep warm.
Heat the clarified butter in a pan until brown and foaming. Pour over the skate, and serve immediately.