Preheat oven to 425º.
Place tortilla strips on a baking sheet lined with foil; lightly coat tortilla strips with cooking spray. Sprinkle strips with 1/2 teaspoon chili powder and 1/4 teaspoon salt. Bake at 425º for 10 minutes or until crisp, and set aside.
Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, cornmeal, onion flakes, and the remaining 1/2 teaspoon chili powder in a shallow dish. Sprinkle fish with 1/4 teaspoon salt; dredge in cornmeal mixture.
Heat 1 tablespoon oil in a large nonstick skillet over medium-high heat. Add fish; cook 3 minutes on each side or until browned and fish flakes easily when tested with a fork or until desired degree of doneness.
Combine romaine and next 4 ingredients (through cilantro) in a large bowl. Combine juice, mustard, and remaining 1/4 teaspoon salt in a small bowl, stirring with a whisk. Gradually add remaining 4 teaspoons oil, stirring constantly with a whisk. Drizzle juice mixture over lettuce mixture; toss gently to coat. Place 1 1/2 cups salad mixture on each of 4 plates; sprinkle each serving with 1 tablespoon cheese. Place 1 fish fillet on each salad; top with 5 tortilla strips.