Heat the grill as hot as you can get it. Meanwhile, mix the melted butter, lemon juice, and Worcestershire sauce, and brush the tuna with the mixture.
Mix the Creole seasoning, salt, and ground anise. Sprinkle generously all over the tuna on both sides. Use all the seasoning.
Grill the tuna for about ninety seconds per side (or less) over the hottest part of the grill. Beware of flames! Turn it once with tongs or a metal spatula (no forks, please).