Pull out chicken from the refrigerator at least 30 minutes before you plan on cooking it, if possible. This will ensure even cooking. Preheat oven to 400 degrees F.
Zest limes and mince garlic. Combine in a small bowl with turmeric, salt, pepper, and olive oil.
Rub chicken thighs with lime/turmeric/salt mixture. You can let the chicken marinate up to 24 hours, or proceed with recipe.
Heat a 10-inch cast iron skillet over medium-high heat. Once you see whispy white smoke, add chicken, skin side down, and cook for 5-7 minutes. Flip chicken over, and slide entire pan into oven. Cook for 20 minutes, or until internal temperature reaches 165 degrees F.
Remove chicken from oven sprinkle and with sumac. Serve with zested limes cut in half, for squeezing over chicken if desired.
*If you use skinless chicken, you may skip the browning step and just bake the chicken for 25 minutes, or until done.