Two bean salad

This is a kitchen-sink-style salad I made the other day, mostly using stuff just lying around the fridge and pantry. It was surprisingly good.

1 can black beans (rinsed)
1 can white kidney beans, rinsed
1 pint grape or cherry tomatoes
1 avocado, diced
2 stalks celery, diced
2 chopped roasted red peppers (from a jar)
1/2 small red onion, diced
parsley to taste
pepper to taste (no need to add salt, beans are probably already salty enough)
oil & red wine vinegar as dressing, to taste

1. Combine everything in a large bowl.

2. Add dressing & toss gently.

What could I have added? A can of tuna would have turned this into a great lunch salad. Also, any kind of bean would do, especially canelloni instead of white kidney.