Furikake is a seaweed seasoning blend, often sprinkled over rice, that can be purchased online or in Asian grocery stores and comes in a variety of flavors, such as wasabi, shrimp or traditional. Hot mustard, both Chinese- and Korean-style, can be purchased online or in Asian grocery stores. Both types will work in this recipe, though we recommend the Korean-style hot mustard for its strong and bright mustard flavor.