1. Preheat broiler.
2. To prepare succotash, cut bell pepper in half lengthwise; discard seeds and membranes. Place pepper halves, skin side up, on a foil-lined baking sheet; flatten with hand. Broil 15 minutes or until blackened. Place in a zip-top plastic bag; seal. Let stand 10 minutes. Peel and finely chop. Combine pepper, onions, and next 7 ingredients (through garlic), tossing to combine.
3. Combine corn and beans in a small microwave-safe bowl; cover with water. Microwave at HIGH 2 minutes; drain. Add corn mixture to bell pepper mixture; toss to combine.
4. To prepare mahimahi, heat 1 teaspoon oil in a large nonstick skillet coated with cooking spray over medium-high heat. Sprinkle both sides of fish with 1/8 teaspoon salt and 1/8 teaspoon black pepper. Add fish to pan; cook 4 minutes on each side or until fish flakes easily when tested with a fork. Serve with succotash.