1. Combine sour cream and salsa.
2. Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add corn, bell pepper, onion, jalapeño, and 1/4 teaspoon salt to pan; sauté 5 minutes, stirring occasionally. Remove mixture from pan; wipe pan clean with paper towels. Combine avocado and juice; toss gently. Stir avocado mixture into corn mixture.
3. Preheat broiler.
4. Sprinkle fish evenly with remaining 1/2 teaspoon salt and black pepper. Place cornmeal in a shallow dish; dredge fish in cornmeal. Heat 1 1/2 teaspoons oil in pan over medium-high heat. Add half of fish to pan; cook 3 minutes. Carefully turn fish over; cook 2 minutes or until fish flakes easily when tested with a fork or until desired degree of doneness. Repeat procedure with remaining 1 1/2 teaspoons oil and fish.
5. Coat both sides of tortillas with cooking spray. Arrange tortillas in a single layer on baking sheets; broil 2 minutes on each side or until crisp. Place 2 tortillas on each of 4 plates. Arrange 2 tablespoons slaw on each tortilla. Divide fish evenly among tortillas; top each serving with about 3 tablespoons corn relish and about 1 1/2 tablespoons sour cream mixture. Serve with lime wedges, if desired.