1. To prepare salad, shave zucchini and yellow squash thinly with a vegetable peeler to equal 2 cups each. Combine lime juice and next 5 ingredients (through sugar) in a medium bowl, stirring with a whisk. Add zucchini mixture, tossing to coat vegetables. Sprinkle with cheese. Set salad aside.
2. To prepare tilapia, pat fish dry with a paper towel. Sprinkle fillets evenly with 1/2 teaspoon salt and pepper. Place egg white in a shallow dish. Combine cornmeal and flour in another shallow dish. Dip each fillet in egg white, and dredge in cornmeal mixture, shaking off excess.
3. Heat a large nonstick skillet over medium-high heat. Add canola oil to pan; swirl to coat. Add fillets to pan; cook 3 minutes on each side or until fish flakes easily when tested with a fork. Top fillets with salad.