First and foremost, get to know someone at your local fish market. Tell him or her exactly what species and cuts of fish you want and ask a lot of questions about its freshness and where it came from. For some popular sushi species, like salmon, FDA regulations require flash freezing at the point of harvest, which kills any undesirables before thawing for the market. Much of the other so-called “sushi-grade” fish receives the same treatment. Ultimately, trust your senses to identify quality fish. The flesh should have a vibrant color, firm texture, and smell like the ocean. Second to quality fish, another common sushi ingredient is nori, the dried seaweed mats used in many sushi recipes, like California rolls. Nori is easy to find and work with, and you can extend the life of a pack by cutting the sheets in half and making smaller rolls with less rice and ingredients.