Combine all ingredients except chicken and whisk together well. Add chicken and toss to coat completely. Cover, and place in refrigerator to marinate 4-24 hours.
Cooking On the Grill
Spray grill with high-heat cooking spray (this is very important, or the chicken will stick). Preheat grill to medium-high.
Place yogurt-coated chicken on the hot grill, and cook about 10 minutes on each side, or until chicken is cooked through (internal temperature should reach 165 degrees F).
Cooking In the Oven
Preheat broiler and move oven rack to be about 8 inches away from the heat. Line a baking sheet with aluminum foil, and place wire rack on top of the foil. Spray the wire rack with cooking spray. Place chicken in an even layer on the wire rack.
Broil for 10 minutes, then turn chicken over. Cook another 10-15 minutes, or until chicken is cooked through and starting to brown. (Juices should run clear, and internal temperature should reach 165 degrees F.)