Cut pork cutlets in half. Pound between wax paper to 1/8-inch thickness.
In shallow baking dish, stir corn oil, lime peel and juice, garlic, cumin, oregano and pepper until blended. Add pork and onion slices; turn to coat. Cover; refrigerate several hours or overnight.
Remove pork and onions from marinade. Grill or broil 4-inches from heat, 6 to 8 minutes or until tender and lightly browned.