In a mixing bowl, combine ground turkey, garlic powder, salt, and oregano and mix well. Squeeze out any liquid remaining from cooked spinach and add to the turkey mix followed by the feta cheese. Mix until spinach and feta are evenly distributed. Divide into four equal portions and form into patties.
In a large skillet, heat the olive oil and medium heat. Once hot, add the turkey burgers. Cook for about 10 to 15 minutes, turning halfway through, or until burgers are firm and no pink remains in the center. Place patties on burger buns, top with sliced tomato and red onion. Drizzle with tzatziki sauce. Enjoy!
For the Tzatziki Sauce
Place the cucumber in a small bowl and sprinkle salt on top and set aside.
In a mixing bowl, combine the remaining ingredients. After the cucumber and salt mix has sat for at least 5 minutes, squeeze out the liquid from the cucumber and add to the yogurt mix. Combine well and serve on top of the turkey burger.
Notes
For a lower carb burger, swap out the bun for a lettuce wrap! Or, enjoy the patty on it's own with a knife and fork.