To make the fennel risotto, trim the bulbs and reserve the fronds for finishing the dish. Peel the fennel stalks with a vegetable peeler. Blanch the fennel stalks in salted boiling water, then drain, refresh under cold water and drain again. Slice and set aside.
Cut the fennel bulbs into 8 mm (¾ inch) dice. Melt the butter in a wide pan and sweat the diced fennel with the olive oil, lemon zest, a squeeze of lemon juice and the star anise. After 3 minutes add the wine and cook until reduced to a syrupy consistency. Add the fish stock and cook until reduced by half. Add the cream and cook until thickened enough to coat the back of a spoon. Take out the lemon peel and star anise, take the pan off the heat and gently fold in the blanched fennel, the chopped fronds, chives, salt and pepper and whipped cream.
Mix together the white peppercorns and sea salt on a plate. Press one side of each tuna steak into the pepper crust and then sear, crust side down first, in a very hot oiled pan. Carefully flip the tuna over to sear the other side.
Arrange the fennel risotto in the centre of the plate. Sauté the calamari for about 30 seconds in