Prepare grill and combine first 6 ingredients.
Divide turkey mixture into 4 equal portions, shaping each into a 1/2" thick patty.
Place patties on a grill rack coated with cooking spray; grill 8 minutes on each side, or until a thermometer registers 165 degrees.
Place lettuce leaves on the bottom halves of each bun; top each with a turkey burger, and one tomato slice.