To prepare aioli, combine first 4 ingredients, stirring well.
To prepare fish, combine milk and egg white in a shallow dish, stirring well with a whisk. Combine cornflakes, flour, salt, and black pepper in a shallow dish.
Heat oil in a large nonstick skillet over medium-high heat. Dip fish in milk mixture; dredge in cornflake mixture. Add fish to pan; cook 4 minutes on each side or until fish flakes easily when tested with a fork. Serve with mayonnaise mixture and lemon wedges.