In a large bowl, mix all ingredients, except the fish and salsa, until smooth. Pour over fish no more than 10 minutes before grilling. The acid in the citrus juice will cook the fish if left for too long.
Lightly oil and heat grill on high heat. Set grate 4 inches from heat. Remove fish from marinade, shake off excess marinade, and discard remaining marinade. Place fish on grill and cook about 9 minutes, or until desired doneness, turning it once. The fish is done when it easily flakes with a fork.
Serve with taco shells or lettuce and salsa. Filling for 5 tacos.
Approximate Nutrient Analysis per serving (based on filling for 5 tacos not including shell or salsa):
220 calories, 16 g fat, 10 g saturated fat, 50 mg cholesterol, 125 mg sodium, 4 g carbohydrate, 1 g fiber, 0 g sugar, 14 g protein