To make the dashi, place the kombu in a pan with 2 litres of water and the bonito flakes. Slowly bring the water to a very gentle boil. Remove the kombu, add another ½ cup water and the bonito flakes and return to the heat. As soon as the water starts to boil remove the pan from the heat and strain the bonito reserving the liquid as stock for the soup.
Drain the arame and place it is a pan with the dashi, mushrooms and noodles. Simmer for 5 minutes. Remove a little of the clear broth from the pan and stir the miso through it to a smooth paste. Pour it into the soup and add the asparagus. Heat gently for another 2 - 3 minutes without bringing it to the boil.
Serve with chopped shallots.
Note: Mugi miso is a fermented paste made from soybeans and barley. Soybeans are a good source of protein and miso is an excellent food for vegetarians who need to boost their intake of protein.