To make the chickpea smash, put the chickpeas in a medium bowl and mash them (a potato masher works well for this). Stir in the onion, celery, pickle, and dill plus any optional additions. To make the dressing, combine the tahini, lemon juice, mustard, and salt in a small bowl. Stir the dressing into the chickpea filling until thoroughly combined. Season with pepper to taste. Enjoy immediately or, stored in a sealed container in the refrigerator, the salad will keep for 3 days.