Rinse fish in cool water and pat dry. Combine 2 teaspoons oil, 2 tablespoons lemon juice and 1 teaspoon ginger and coat both sides of fish. (Refrigerate for up to an hour.) To prepare Pineapple Salsa, heat remaining oil in a medium skillet. Add yellow pepper and onion and saute until soft. about 4 minutes. Add crushed pineapple, raisins, cayenne and remaining lemon juice and ginger; saute until pineapple is warm, about 4 minutes longer. (Salsa can be made ahead up to 24 hours; but bring to room temperature before using.)
Grill fish 4 to 5 inches from hot coals, turning once, until fish is barely opaque in the center, and just begins to flake when tested with a fork about 2 minutes per side for 3/4-inch thick fish steaks. Divide spinach and romaine among six plates and place a grilled fish steak on each. Top with pineapple salsa as a dressing.