Combine lemon juice, oil, 1 clove of the garlic, mustard and oregano in a plastic bag or plastic container, add chicken. Make sure both sides of the chicken get some marinade on it. Close container and refrigerate for at least a hour.
In a small bowl combine cucumber, yogurt, sour cream dill and remaining garlic. Cover and refrigerate until serving.
Pour chicken and part of the marinade in a nonstick skillet. Cook for until the juices are dried up and the chicken is done.
While the chicken was cooking I diced up the onion and tomato.
We put spread the chicken out between four pitas. We could have used a little more chicken but we are trying to cut back on portions some so it was fine with both of us.
Top with cucumber sauce, diced red onion and diced tomato.