Melt butter in a saucepan and add lemon juice and tarragon. Sprinkle swordfish with salt and pepper and brush oil over grill grate. Brush butter mixture over swordfish and grill on a medium-hot grill for 8 - 10 minutes per side. Serve with lemon wedges. If you are opposed to eating swordfish, you may substitute any firm white fish.
Chefs Notes: Not much room for improvement here.