In a small bowl, whisk together the Greek yogurt, lemon juice, garlic powder, dill, and a pinch of salt. Cover and chill in the refrigerator.

Chop the sun-dried tomatoes and red onion. Crumble the feta cheese and squeeze moisture from the spinach. Combine all ingredients in a bowl along with the oregano and additional garlic powder.

In a large mixing bowl, combine the ground turkey with the mixture from step 2. Mix gently until just combined.

Divide the mixture into five equal portions and shape into patties, making indentations in the centers.

Heat oil in a skillet over medium heat. Cook the patties for 5-7 minutes on each side until golden brown and the internal temperature reaches 165°F.

Let the patties rest, then assemble each burger with a patty, a dollop of Greek yogurt sauce, and slices of cucumber.