In a small bowl, mix all spices for Greek seasoning.
In a large bowl, mix ground turkey and Greek seasoning together until well combined.
Divide into four balls then press gently to form patties.
Place burger patties on baking sheet and into the refrigerator for 30 minutes to 1 hour to let set.
Heat olive oil on a griddle or skillet over medium heat.
Grill turkey burger patty on each side for 8 minutes.
Make Homemade Tzatziki Sauce according to instructions. Add sauce to a food processor and pulse a few times to make into a thinner consistency.
Serve burger on toasted whole wheat sandwich buns, top with slices of roma tomato, romaine lettuce, a tablespoon of Homemade Tzatziki Sauce and a sprinkle of reduced fat feta cheese.