1. Preheat the oven to 190°C. Lay 2 overlapping slices of prosciutto on a board and place a fish fillet on top, skinned side up. Combine the breadcrumbs with the hazelnuts, coriander, eggs and a little pepper. Spread one-quarter of this mixture on top of the fish, pressing it over evenly. Carefully roll up the fish and prosciutto like a swiss roll. Repeat with the remaining prosciutto, fish fillets and hazelnut filling.

2. Arrange the fish rolls in a lightly greased ovenproof dish. Pour over the wine. Using 15 g of the butter, put a dab on top of each roll. Cover tightly with foil and bake for 20–25 minutes, or until the fish flakes easily.

3. Meanwhile, put the potatoes into a large pan and pour over boiling water to cover. Cook over a moderate heat for about 15 minutes, or until tender.

4. Drain and mash the potatoes, then beat in the milk, remaining 15 g butter and the rocket, and season to taste. Transfer to a serving dish and keep hot. Steam the asparagus for about 4 minutes, or until just tender.

5. Serve the fish, cut into slices, on individual warmed dinner plates, with the asparagus and potatoes.