Butterfly the squab: Place the bird breast side down on a cutting board.

Using poultry shears, cut along both sides of the backbone to remove it.

Turn the bird over, breast side up.

Pull the body open and press down firmly, cracking the rib bones slightly, until the bird lies relatively flat.

Make the marinade: In a small bowl, whisk together the bourbon, vegetable oil, lemon juice, thyme, lemon zest, salt, and pepper.

Place the squab in a large plastic zip-lock bag and pour in the marinade. If necessary, use two bags and divide the marinade.

Press the air out of the bag and seal tightly.

Turn the bag to distribute the marinade, place in a bowl, and refrigerate for 2-12 hours, turning occasionally.

Make the baste: In a small bowl, whisk together the maple syrup (or honey), bourbon, and Dijon mustard.

Set the baste aside.

Remove the squabs from the bag and discard the marinade.

Pat the squabs dry with paper towels.

Lightly brush with vegetable oil.

Grill the squabs, skin side down, over indirect medium heat until the skin is golden brown and the juices are still slightly pink, about 35-45 minutes, turning once halfway through grilling time.

During the last 10 minutes of grilling, brush on the baste.

Serve warm.