Spicy Hot Grilled Salmon

1/2 C finely chopped onions
1/4 C chopped fresh cilantro
1 T sugar
1/2 C unsweetened pineapple juice
1/2 C lime juice
2 T low-sodium soy sauce
3 serrano chilies
3 cloves garlic, coarsely chopped
4 salmon steaks

Blend all ingredients except salmon in a food processor or blender until smooth. Pour over fish and marinate, covered, in the refrigerator for 6 to 8 hours. Remove salmon from marinade (reserve for basting) and cook it on a grill or under a broiler; the fish is done when it flakes easily with a fork. Baste fish often during cooking with reserved marinade.