Add a squeeze of lemon, dill, garlic and finely chopped cucumbers to an 8 oz container of greek yogurt, mix well. Add salt and pepper to taste if desired.
Burgers
Preheat the grill to a medium high heat. Squeeze excess moisture from the spinach. In a medium bowl combine turkey, feta, garlic powder, oregano, salt and pepper and mix well. Make four 4-inch patties.
Oil the grill grates. Grill the burgers until cooked thoroughly flipping half way through 4-6 minutes per side (an internal temperature of 165 degrees on an instant read thermometer).
Place the buns on a serving platter, top each one with 1 dollop of tzatiki sauce, 3 cucumber slices, 2 onion rings and a tomato slice.
These work great to make ahead of time, wrap individually and refrigerate up to 8 hours.