Dashi is the basic stock recipe used in traditional Japanese cooking to make soups, to simmer food, or making rice. There are several methods to creating it, I use the following recipe below and it serves me well. Katsuobushi (fermented bonito fish)*if you are allergic to mold, you will not want to use this ingredient)) is traditionally used to make dashi, but difficult to find in my area, thus it is not included in this recipe.
4 cups of cold water
1 sheet of kombu (seaweed)
1 1/2 cups of shiitake mushrooms
1/2 cup of mirin (Rice alcohol)
1/4 cup of tamari
1/4 cup of crushed ginger
Place kombu in cold water and heat on medium. Before water begins to boil, remove kombu and discard. Add mushrooms and simmer for 30 minutes on low. Add in remaining ingredients. Strain broth and either discard mushrooms or save for use in another dish or toss with noodles.
This stock works well for whatever dish you are preparing that night, and will store in the refrigerator for up to three days, but quickly loses its flavor.