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

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

Add ground beef along with cumin, oregano, paprika, salt, and black pepper. Cook until the beef is nicely browned and cooked through, about 5-7 minutes.

In a separate bowl, whisk together plain Greek yogurt, lemon juice, and a pinch of salt until smooth and creamy.

Warm the pita breads in a dry skillet or microwave until soft and pliable.

Fill each warm pita with the cooked beef mixture, then add chopped tomatoes, sliced cucumber, and a sprinkle of fresh parsley.

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