In a skillet, lightly toast the walnuts, just until they’re fragrant. If you’re making this at home, you can do this in the oven.
In a large bowl, mash the chickpeas until they’re a bit broken down.
Add the mayo, mustard, bell pepper, carrots, celery, and walnuts to the bowl of chickpeas and mix well. Add salt and pepper to taste. Serve in sandwiches or with crackers.