This ginger-scallion sauce uses jarred pickled ginger (gari) in place of fresh for a brighter spin on the good-on-everything staple. Usually served in a twisted heap alongside a platter of sushi, gari is meant to cleanse the palate between bites of fish and rice. It’s that same refreshing quality that works so well in this sauce, with the sweetness and acidity of the pickles mellowing the sharper bite of raw scallions. Salt the cucumbers ahead of time, but dress the salad just before eating for a well-seasoned salad that still has some crunch.