Wash the vine leaves and wrap them around the slices of fillet stopping them with a toothpick. Brown in a small frying pan with the butter. Perfume with the sprigs of wild fennel and the lemon peel.
When they begin to brown, baste with half a glass of prosecco and allow it to evaporate.
Salt and pepper. Then cover the fillets with the grapes squeezed and filtered to eliminate the peel. Finish cooking.
When cooked remove the fillets and filter the sauce, diluting with a glass of prosecco. Add ½ a spoonful of flour and allow to thicken on the heat.
Spread the sauce and lay out the fillets still covered with the vine leaves. Sprinkle with freshly ground black pepper and fresh wild finocchietto.