Thinly slice the celery (if it’s a large rib, cut in half lengthwise first). Thinly slice the green onions as well.
Combine the chickpeas with the chopped celery and green onions, garlic powder mayonnaise and lemon juice. If the salad is dry, add more mayonnaise (cooked chickpeas have a drier texture than canned).
Assemble the chickpea salad sandwich. Top the sandwich with lettuce or greens and chickpea spread.