Place the chicken pieces in a large ziptop bag or 9x13-inch pan.
In a small mixing bowl, whisk together the yogurt, buttermilk , lemon juice, olive oil, and seasoning mix. Pour this mixture over the chicken pieces, turning the chicken to coat.
Seal the bag or cover the pan and refrigerate the marinating chicken pieces for 2 hours to overnight. You can also freeze the chicken and marinade in a freezer bag at this point. Thaw before continuing.
Heat an outdoor grill or indoor grill pan.
Remove the chicken from the marinade and place on the hot grill. Cook, turning once, until the chicken is cooked and has reached an internal temperature of 165 degrees. Remove the chicken from the grill and tent with foil for 10 minutes so that it can finish cooking. Serve hot or cold.
Nutritional values are approximate as chicken does not absorb all the marinade.Refrigerate leftovers promptly and store in an airtight container in the refrigerator for up to 4 days.