Japanese miso and noodle soups are traditionally judged by the quality of their dashi, which is a stock made from kombu (dried kelp seaweed) and bonito flakes (shavings of dried smoked tuna). You can find bonito flakes at the supermarket and dried kelp in Asian shops.
This is the base for miso soup (among other recipes) and is what makes the soup so good! Thank you for the easy recipe! - 01 Feb 2010 (Review from Allrecipes USA and Canada)
Easy to make. I used dried kelp knot instead. - 16 Apr 2011 (Review from Allrecipes USA and Canada)