Sesame Ginger Barbecued Chicken

1/3 cup plum sauce or sweet and sour sauce
1/4 cup water
3 tablespoons hoisin sauce
1 1/2 teaspoons sesame seed, toasted, if desired
1 clove garlic, minced
1 teaspoon grated fresh ginger or 1/4 teaspoon ground ginger
1/4 to 1/2 teaspoon Oriental chili sauce or several dashes bottled hot pepper sauce
6 small skinless, boneless chicken breast halves and/or thighs; about 1 1/2 pounds total

For sauce, in a small saucepan combine all of the ingredients except the chicken. Bring to boiling over medium heat, stirring frequently; reduce heat. Simmer, covered, for 3 minutes. Set aside.