Prepare the tzatziki: Grate the cucumber and squeeze out all excess liquid using a clean towel. Mix with Greek yogurt, lemon juice, garlic, dill, salt, and pepper. Refrigerate until ready to serve.

Heat olive oil in a large skillet over medium-high heat. Add diced onion and sauté for 3 minutes until soft.

Add minced garlic and cook for 30 seconds until fragrant.

Add ground beef to the skillet. Break it apart with a wooden spoon and cook until fully browned.

Stir in oregano, cumin, coriander, paprika, salt, and pepper. Cook for 1 minute to bloom spices.

Stir in tomato paste and beef broth. Simmer for 2-3 minutes until the liquid reduces and coats the meat.

While beef finishes, warm the pita bread in a separate dry skillet or toaster oven until soft and pliable.

To assemble, pile beef onto warm pita. Top with tzatziki, tomatoes, sliced onions, feta cheese, and parsley.