In 3.5-quart salad bowl or soufflé dish (preferably straight-sided), layer salad as follows: bell pepper, onion, lettuce, cheese and three bean salad.
Mix together the mayonnaise, sour cream and chipotle peppers. Spread over top of salad. Cover and refrigerate up to 8 hours.
Just before serving, sprinkle top with chips and sliced avocado, if desired. Toss to serve.
Note: Read Four Bean Salad can be substituted for Three Bean Salad.