In a bowl, mix the chicken pieces with sumac, olive oil, garlic powder, onion powder, salt, and pepper. Ensure chicken is well coated.
Heat a large pan on medium-high heat. Add chicken and cook for 6-8 minutes, turning occasionally, until cooked through and no longer pink.
While chicken cooks, prepare the sauce. In a small bowl, mix Greek yogurt, parsley, mint, lemon juice, salt, and pepper. Adjust lemon or salt to taste.
Warm flatbreads in a pan, microwave, or oven until soft and pliable.
Lay out a flatbread and spread with yogurt sauce.
Add chicken, tomatoes, cucumbers, and red onion.
Fold in sides of flatbread, then roll up from the bottom to create a wrap. Do not overfill.
Cut in half if desired and serve.