Ingredients For that grain: 3 cups short-grain Japanese grain, rinsed 1/3 cup grain vinegar 3 tablespoons sugar Salt For that rolls: 10 nori sheets (dried seaweed), halved Sesame seeds, for sprinkling 1 cucumber 1 avocado 1 plum tomato, seeded 1 small red onion 20 asparagus spears, trimmed and