Mediterranean kefta lamb burgers on grilled pita

Ingredients

• 1 lb ground lamb
• 3 tablespoons finely chopped fresh parsley
• 3 tablespoons finely chopped fresh mint
• 3 tablespoons finely chopped red onion
• 1 teaspoon dried oregano
• 200 g feta cheese, cubed
• 2 pita breads, cut in half and opened
• 2 tomatoes, sliced
• 4 Lebanese cucumber, sliced
• Romaine heart leaves
• Salt and pepper from the mill
• 1 1/2 cups Greek yogurt
• 1 clove garlic, finely chopped
• 1/2 cup peeled and seeded cucumber, finely chopped
• 4 tablespoons finely chopped fresh mint
• 1 tablespoon lemon juice
• Salt and pepper to taste