Grate lemon rind from lemon, avoiding the pale bitter pith, into a large bowl; squeeze lemon juice into bowl. Stir in milk and next 3 ingredients until blended.
Rinse fillets, and pat dry with paper towels. Add fillets to lemon mixture in bowl; cover and chill 1 hour.
Place cornmeal on a large plate or in a large shallow dish. Turn fillets in lemon mixture until thoroughly coated; dredge in cornmeal, coating evenly.
Cook fillets in hot oil in skillet over medium-high heat 4 minutes on each side or until browned. Remove from skillet. Garnish, if desired.
