Whisk together the sauce ingredients in a small bowl and refrigerate for 1 to 2 hours. Place the fish in a lightly oiled baking dish. Combine the olive oil, horseradish, soy sauce and garlic in a small bowl, and brush on the fillets. Cover the fish and marinate for 1 to 2 hours in the refrigerator. Preheat the oven to 425 degrees. Bake the fish for 15 minutes or until desired doneness. Serve with Horseradish Sauce.