In a shallow bowl, mix vinegar, mustard, garlic, and pepper. In another shallow bowl, stir together panko, cheese, and mint.
Trim excess fat from lamb and discard. Rinse chops and pat dry. One at a time, turn chops in vinegar mixture to coat well; lift out and press firmly in panko mixture, turning to coat all sides. Place chops slightly apart in a lightly oiled 10- by 15-inch pan; drizzle evenly with butter.
Bake in a 500° regular or convection oven until coating is browned and meat is medium-rare (pink) in center of thickest part (cut to test), 10 to 14 minutes, turning once after 5 minutes. Serve with mint aioli and season to taste with salt.