First take the kombu and cut it into smaller pieces. Then pour the water into a big pot. Now add the kombu leaves and let this sit for 4 hours to 5 hours.
Then bring this to a simmer on a medium heat. While it’s coming to a simmer scoop off the white foam with a ladle.
Once the broth is almost at a simmer, let’s say 90 degrees Celsius gently remove the kombu.
Then add the bonito flakes and bring this to a simmer.
Once it’s simmering, turn off the heat and let it marinade for 15 minutes.
Meanwhile transfer the chicken wings on an oven rack and also add the chicken bones. Toast them at 200 °C for one hour till nice and golden.
Once the bonito has marinated pass it through a fine sieve. Now pour the dashi back into the pan and add the toasted chicken. Let this simmer for 90 minutes.
After those 90 minutes also add the dried shiitake mushrooms and let it simmer for 1 more hour.
Then drain the broth and let it sit for at least 30 minutes, so you don’t waste a single drop.
Meanwhile trim the end from the spring onions and wash them. Now chop them. Then take the onions, cut them in half, clean them and chop them.
Once that’s done pour the dashi back into the pan and add the chopped spring onion and onion. Let this simmer for 90 minutes.
Then pass the dashi through a fine sieve and let it sit so you don’t waste a single drop.
After that bring it to a simmer once more and use a ladle to remove the chicken fat.
