This recipe is for the dark sweet sauce served over many types of sushi in restaurants, especially seafood and fish. Tsume is traditionally made with the reduced stock of boiled conger eels (anago). This abbreviated recipe tastes great and takes much less cooking time than the traditional method of preparation. Dashi is a soup and cooking stock considered fundamental to Japanese cooking. Dashi forms the base for Miso Soup, clear broth soups, Japanese noodle broths, and many Japanese simmering liquids. Most people use granulated or liquid instant substitutes found in Asian Markets. A small pastry brush or rubber spatula will allow you to apply this sauce thinly and evenly over your sushi or other choices. American sushi chefs use Tsume to dress everything from avocado-based rolls to tamago. This recipe will keep in the refrigerator for several months. Heat to ambient temperature (or warmer) before use.