Dashi is stock or broth that made out of sea cabbage (kombu), dried‐bonito shavings, dried mushrooms, chicken bones, and so on.
To make dashi, the component of those materials is dissolve in warmed or boiled water.
Although there are many kinds of materials for making dashi, we usually use sea cabbage (kombu) and dried‐bonito shavings for miso soup.
Making dashi takes time and it’s sometimes difficult or expensive to buy sea cabbage (kombu) so I recommend to use dashi (stock) granules or dashi (stock)-containing miso. I always use them for daily cooking.