Cut shrimp in half, or just break them up a bit later on when you stir everything together. Transfer the shrimp to a large mixing bowl; set aside.
Add the celery (if using) and the onion to the bowl with the shrimp, tossing to evenly combine.
In another mixing bowl, add the remaining ingredients. Whisk them together until the mixture's a smooth dressing.
Pour the dressing out over the shrimp. Toss until everything's evenly combined and well coated.
Cover the bowl tightly with cling wrap, and chill/refrigerate the shrimp salad for an hour, and up to 5 hours before serving.
Serve the prepared, chilled shrimp salad on bed of lettuce as wrap, or on toasted bread as a sandwich. It can also be chopped up a bit and enjoyed as a delicious cold dip with buttery crackers.