1. In a medium saucepan, melt the margarine or butter
2. Add green pepper, celery and onion and saute until limp, about 5 minutes.
3. Add chicken and saute until heated through.
4. Stir in the barbecue sauce and simmer for a few minutes until bubbly.
5. Spoon chicken mixture equally on the split toasted bun bases and cover with the tops.
6. Serve immediately.