In the bowl of a food processor, add the beans, peppers, walnuts, garlic, harissa, olive oil, vinegar, Kosher salt, and freshly ground black pepper. Process until as smooth as possible, about 1 minute. Taste and season with more salt and pepper, if needed.
Notes
Dip can be made ahead and stored in an airtight container in the refrigerator for up to 1 week.