Whisk all ingredients together. Cover and refrigerate. (Sauce can be made well ahead of time.) Cut the breast halves into 1 1/2 inch cubes and thread them on the skewers. Season the kebabs with a little salt and pepper and drizzle with a little olive oil. Light your grill to medium heat and oil the grates well. Reserve 1/2 to 3/4 cup of the sauce for dipping. Place your kebabs on the grill and start lightly basting and turning until the chicken is done. (Be careful not to burn!) Serve them up with a little of the reserved sauce on the side.