You need a zucchini and a cucumber. I got this lemon cucumber from our CSA. I forgot to take a picture of the zucchini, but I think you know what they look like.
My celery is still pretty small so I used several stalks. Usually, I would use 3 regular sized stalks so that I have equal parts zucchini, cucumber, and celery.
Add the steamed cucumber, zucchini, and celery to the food processor and give it a whirl.
Add a bit of salt after transferring to individual bowls. This makes two large servings or 4 small servings.