In the meantime, wash the fennel, remove the stalk. Put aside a few stalks with leaves. Chop the rest of the leaves, then also put aside. Thinly slice the fennel bulb, stew in a pot with the white wine and a pinch of salt for about 10 minutes. Drain, set the cooking liquid aside.
Peel and finely dice the shallots. Sauté in the olive oil at a medium heat until they are slightly brown. Add some of the cooking liquid, stir in the chopped fennel leaves and quickly bring to the boil. Leave to cool, thicken with the sour cream. Season with the salt, pepper and grated lemon peel. Do not reheat! Arrange the fennel on the plates with some sour cream sauce, add two fish rolls to each plate and garnish with a lemon wedge and some fennel leaves. Serve with boiled potatoes or bread.