1. Combine the drained chiles, scallion, garlic, plum sauce, soy sauce, sesame oil and salt in a food processor or blender. Whirl until pureed.
2. Place chicken in a medium-size bowl. Add half of plum-sauce mixture. Cover and refrigerate for 1 hour to marinate. Reserve the remaining half of the plum mixture.
3. Soak 16 small wooden skewers in a bowl of cold water for 15 minutes to prevent scorching during cooking.
4. Heat broiler. Thread green pepper, onion, red pepper and chicken cubes on skewers. Place skewers on rack in the broiler pan. Spoon on the remaining reserved plum mixture. (Can be made up to 2 hours ahead and refrigerated.)
5. Broil 6 inches from heat for 6 to 8 minutes or until chicken is cooked through, turning once. Makes 16 skewers.