Preheat the oven to 220ºC/200°C Fan/gas mark 7/425ºF.Scatter the chopped rosemary and the lemon zest onto a chopping board, and then roll the monkfish fillets in the delicate mixture. The dampness of the fish should make everything stick.Wrap the monkfish fillets with the cat's-tongue-pink prosciutto, rather as if you were putting on a ham bandage, letting the thin pieces overlap a little so that the fish stays covered.Drizzle the oil in a shallow roasting tin and place the Parma-ham-covered fish in the tin. Roast for 15 minutes or until the fish is just cooked.Take the tin out of the oven, transfer the fish to a board and let it rest for 2 or 3 minutes, while you arrange a bed of red leaves on a serving platter (dribbling a little extra-virgin olive oil and squeezing some lemon juice over the salad, if wishes). Then carve the fish into chunky diagonal slices, taking care to keep the ham in place around it (this is not as difficult as it sounds), place these on the leaves and serve immediately.