Cut each chicken thigh into 12 small pieces. On a bamboo skewer, place 3 pieces of chicken alternately with 1 piece green bell pepper and 1 piece red bell pepper. Set aside.
In large shallow baking dish, combine all remaining ingredients except the orange to make marinade. Dip chicken skewers in mixture to coat; arrange skewers in baking dish, cover and marinate for at least 2 hours or overnight.
At cooking time, prepare Cranberry Plum Sauce; keep warm until needed. Drain chicken. Place skewers over hot charcoals, grilling for 3 to 5 min.; turn once or until chicken is done, about 2 minute on each side. (Or, broil skewers for 4 min., turning skewers once to cook about 2 minute on each side.).
Arrange on serving platter around bowl of Cranberry Plum Sauce. Garnish with orange slices.
Cranberry Plum Sauce: In medium saucepan, mix all ingredients. Whisk mixture over medium heat until well-blended and hot. Pour into small serving bowl. Serve warm with chicken.