1 cup Greek yogurt
½ cucumber, quatertered
1 teaspoon dill weed
1 clove garlic, minced
½ teaspoon lemon juice
1 teaspoon red wine vinegar
½ tablespoon olive oil
⅛ teaspoon ground black pepper
Pinch of salt
Slice chicken breasts into thin strips. Add chicken breast strips, 2 tablespoons olive oil, 3 cloves minced garlic, 1 tablespoon lemon juice, 1 teaspoon vinegar, and oregano to a large plastic bag and shake well. If you do not have a bag, place everything in a large bowl. Refrigerate for 1 hour.
Add all ingredients for tzatziki sauce, except for ¼ cup of the chopped cucumber, to a blender and pulse. Stir in reserved cucumber. Cover and chill in a refrigerator until ready to serve.
Preheat oven to broil setting, then add chicken to a broiler pan (if you do not have one, just grease a baking sheet).
Broil the chicken for 3 minutes on each side, then remove from the oven.
Warm flat bread in a toaster oven on the light setting if desired.
Top the flat bread with lettuce, red bell pepper, and chicken strips. Drizzle with tzatziki just before serving.