Place in a small saucepan over a medium heat the butter, sugar, garlic, lemon juice, soy sauce and pepper.
Stir this mixture occasionally and remove from heat as soon as all the sugar has dissolved.
Lightly oil your preheated barbecue with some oil and just before you place the halibut steaks on to it lightly brush each side with the sauce you made earlier.
Cook each side of the fish for about 5 minutes or until the flesh of the fish can be flaked easily with a fork.
Whilst the fish is cooking make sure that you keep basting with the sauce.
Once the fish is cooked serve to your guests on a plate with some warm new potatoes and a crisp green salad.
Otherwise you may want to consider serving the fish with some rice.