Preheat oven to 500°F (260°C).

Prepare a lemon juice and water mixture in a bowl.

Soak fish fillets in the lemon juice mixture.

In a shallow dish, combine egg whites.

In another shallow dish, combine flour, salt, and pepper.

Remove the fish fillets from the lemon juice mixture and pat dry.

Sprinkle each side of the fish with the flour mixture.

Dip the floured fish in the egg whites.

Dredge the fish in cornmeal or cornflake crumbs, ensuring it's fully coated.

Place the breaded fish fillets on a baking sheet.

Drizzle vegetable oil over the fillets.

Bake in the preheated oven for 12-15 minutes, or until golden brown and cooked through.

Serve immediately with lemon wedges, if desired.