1. Grate the cucumber over a tea towel. Squeeze out as much liquid as possible.
2. In a bowl, combine the grated cucumber, feta cheese, yogurt, lemon juice, dill, ½ teaspoon of the minced garlic, and a pinch of salt. Stir everything to combine and then refrigerate while preparing the burgers.
3. Squeeze as much moisture as possible from the frozen spinach. Roughly chop the spinach. Grate the red onion and squeeze out as much moisture as possible.
4. In a bowl, combine the ground turkey with the spinach, onion, sun- dried tomatoes, egg, panko, oregano, remaining ½ teaspoon garlic, salt, and pepper to taste. Stir everything until it is evenly combined. Shape the mixture into 4 even patties.
5. Cook the burgers on a stove top grill, in a nonstick skillet, or over an open flame for about 5 minutes on each side over medium-high heat.
Layer the bottom half of the bun with lettuce, a thick slice of tomato, the burger patty, and the yogurt sauce before adding the bun top. Serve