Season grouper fillets with salt and pepper. Sear in 1 tablespoon butter, then finish in oven at thermostat 8 (240°C) for 10 minutes.
Finely julienne the white parts of well-washed leeks. Sauté until golden; drain and reserve.
Plate 5 grouper slices in a fan shape, with cooked leeks mounded at the base.
Reduce veal jus, season, whisk in remaining butter. Off heat, add truffle juice to warm and glaze fish.
Garnish with chive sticks in the leek mound.
