Cut the chicken thighs into 1-inch (2.5-cpieces.
In a large bowl, whisk together the yogurt, oil, vinegar, garlic, oregano, turmeric, salt, and red pepper flakes.
Add the chicken and stir to coat. Cover and marinate in the refrigerator for at least 1 hour and up to 8 hours.
Preheat an outdoor grill or grill pan to medium-low heat.
Thread the chicken pieces among 4 wooden or metal skewers, discarding the marinade in the bowl.
Sprinkle with salt and pepper.
Grill the chicken, turning the skewers occasionally, until golden brown and cooked through in the center, about 15 minutes.