1. Adjust oven rack to middle position. Heat oven to 350 degrees.
2. In a small bowl, mix sour cream, yogurt, cucumber,lemon juice, 2 minced garlic clove, feta, pepper to taste;.
3. Wrap pitas in foil and Place in oven; bake until warm and pliable, 5 minutes. Cut in half.
4. Meanwhile, heat oil in a large skillet over high heat saute onion until golden brown. Add meat, oregano and remaining minced garlic; continue to saute for about 2 minutes.
To serve first fill pitas with lettuce, followed by meat, tomatoes and cucumber sauce.