In small bowl, mix 1/2 cup yogurt and remaining sauce ingredients; refrigerate until serving.
Heat gas or charcoal grill.
In medium bowl, mix all burger ingredients and remaining yogurt. Shape mixture into 4 patties, about 1/2 inch thick.
Place patties on grill over medium heat. Cover grill; cook 8 to 10 minutes, turning after 5 minutes, until thermometer inserted in center of patties reads 160°F.
Place burgers in buns with tomato slices and sauce.
If you choose to broil your burgers instead, broil patties with tops about 6 inches from heat 4 minutes; turn patties. Cook 6 to 8 minutes longer or until meat thermometer inserted in center of patties reads 160°F.
Place a patty on one of the sandwich thins, top with 1 tbsp of Tzatziki sauce, a few tomato slices and a few fresh lettuce leaves.
Notes
The entire recipe makes 4 burgersServing size is 1 Greek Turkey burger with bun, 1 tbsp Tzatziki sauce and lettuce/tomato