In a large non-stick skillet, heat oil and add chicken. Cook for 4-6 minutes per side or until done.
While chicken is cooking, mix yogurt, mint leaves, lemon juice, and a pinch of salt and pepper in a small bowl. Set aside.
Slice cucumber, tomatoes and onion.
When chicken is cooked, remove from heat and set aside.
In a clean skillet, toast pita breads one at a time until heated.
Layer chicken, yogurt sauce, cucumber, tomato and onion on pita bread. Garnish with fresh cilantro.