Grilled Halibut Marinade

A co-worker of mine went fishing in Alaska and brought me back some fresh halibut. This recipe came from the internet - not sure which site.

1 lb. halibut
2 Tbsp. butter
1 large red onion, chopped
4-5 cloves garlic, sliced
1 tsp. salt
1 Tbsp. chopped chives
2 lemons, zested & juice from ½ lemon
½ tsp. chopped dill
½ c. white wine
2 Tbsp. olive oil
2 Tbsp. capers

Sautee butter, onion & garlic over med. heat until translucent. Add salt, chives, lemon zest, lemon juice, dill & wine and cook until reduced by 1/3. Add oil & capers and stir. Remove from heat. In a large foil square, place spoonful of sauce. Add piece of fish, cover w/ more sauce and wrap tightly. Grill each side for 3 minutes.