Add the garbanzo beans to a food processor and pulse 5 to 10 times, or until they're chopped and take on a flaky texture. Do not over-process. Transfer to a large serving bowl.
Next, add the artichoke hearts to the food processor. Pulse about 10 times, or until they're chopped and take on a flaky texture. Carefully gather the chopped artichokes within your hands or within a piece of cheesecloth, and press the excess water from them. They don't need to be completely dry, but you want to release any excess liquid to ensure a more "meat-like" texture. Add to the bowl with the garbanzo beans.
Stir in the red onion, celery, grapes, vegan mayonnaise, and lemon juice.
Season to taste with sea salt (I usually add a 1/2 teaspoon) and black pepper.
Serve on its own, tucked into pita bread, or on top of sandwich bread, baguette slices, crackers, cucumber slices, etc.
Cover and refrigerate leftovers for up to 2 days.