For the marinade
1 large chicken breast (about 1/2 pound)
1/2 cup plain, whole milk yogurt
2 tablespoons olive oil
1 teaspoon dried oregano
1/2 teaspoon kosher salt
Freshly ground black pepper, to taste

For the Greek sauce
4 tablespoons mayonnaise (regular or light)
1 tablespoons milk
1 tablespoon cider vinegar
3/4 teaspoon sugar
1/8 garlic powder
Squeeze of lemon juice
Kosher salt and freshly ground black pepper

For the chicken
2 tablespoons olive oil
2 large garlic cloves, peeled and smashed
1/2 teaspoon dried oregano
1 tomato, diced
1/2 cucumber, diced
Pita bread, for serving