Preheat oven to 350* (for croutons)
Wash romaine and dry completely. Cut vertically (think lengthwise) into portions.
Heat up grill to medium high heat and grease the burners with avocado oil (higher melting point).
Cut red onion into rings.
Lightly Spray lettuce and onion with avocado oil. Add small sprinkle of salt.
Grill romaine for 3 minutes on one side, pressing down with tongs to get a nice sear. Flip and grill 2 minutes on the other side. Grill onions until tender.
Remove from grill, add a light squeeze of lemon juice, and top with chicken, onion, and croutons.
Once cooled, drizzle caesar dressing over the top.