For the relish:
Combine all the ingredients and stir. If making ahead, stir in the pistachios right before serving.
For the chicken:
Combine all the ingredients (except the chicken) in a medium sized bowl.
Stir to combine.
Add the chicken and stir to thoroughly coat.
Marinate 2 hours or overnight.
Thread chicken onto metal or bamboo skewers (if using bamboo, soak in warm water for 30 minutes before using).
Grill or broil for 5-6 minutes a side until chicken is cooked through.
Serve with the relish and plain yogurt if desired.
Combine all the herbs and spices in a small bowl. Extra seasoning may be stored in a small, covered container at room temperature.