Make my homepage tzatziki greek yogurt sauce and store in fridge until ready to serve. Make my gluten-free almond flour naan-style flatbread at least one hour before serving so they have a chance to cool and set.
Place 2 chicken breasts in a plastic bag and lightly pound them to about 1/2 inch thickness. This step is optional but helps tenderize the meat and allows better marinade absorption. Remove from bag and dice into 1/2-inch pieces. Lightly salt the chicken pieces.
In the same plastic bag, combine 1/4 cup Greek yogurt, 2 tablespoons white wine vinegar, 2 tablespoons lemon juice, 2 tablespoons light olive oil, 1 tablespoon oregano, 2 teaspoons garlic powder, 1 teaspoon onion powder, 1 teaspoon salt, and 1/8 teaspoon black pepper. Squish the bag from the outside to mix everything together.
Add the diced chicken pieces to the marinade bag. Seal tightly and massage to coat all pieces evenly. Refrigerate for at least 2 hours or up to 24 hours for maximum flavor.
Remove the marinated chicken and spread on paper towels. Dab off excess marinade—this step is crucial for proper browning. Heat a large skillet over medium-high heat and add 2 tablespoons light olive oil. Add chicken pieces in a single layer and sear for about 2 minutes per side until golden brown and cooked through.
Prepare 1 cup shredded romaine lettuce, 1 cup halved cherry tomatoes, 1 cup diced cucumbers, and 1/4 sliced red onion.Layer each pita or naan with tzatziki sauce, lettuce, cucumber, tomato, red onion, cooked chicken, more tzatziki sauce, and feta cheese. Serve immediately.