Heat olive oil in a skillet over medium heat. Add finely chopped onion and sauté for 3-4 minutes until translucent.

Stir in minced garlic and sauté for about 30 seconds until fragrant.

Add ground beef, cumin, oregano, paprika, salt, and black pepper. Cook for 6-8 minutes until browned, breaking up beef as it cooks.

In a small bowl, combine Greek yogurt, lemon juice, minced garlic, and a pinch of salt. Whisk until smooth.

Warm pita breads in a skillet over low heat for 1-2 minutes on each side.

Open each pita and fill with beef mixture, chopped tomatoes, sliced cucumber, and parsley.

Drizzle the lemon garlic yogurt sauce over the filled pitas and serve immediately.