Lightly rinse kelp; check for tiny shells.
In a soup pot, cover kelp with water and simmer for 10 minutes.
Remove and cut the kelp into small pieces.
Return to the pot with the onion and squash; add water to cover.
Simmer for 20–30 minutes until squash is soft, or pressure cook for 5–10 minutes.
6. Purée miso with broth; add to pot. Garnish with parsley.
Omit parsley, add broccoli flowers and/or kale; cook until bright green.
If, for appearance's sake, you wish to have no kelp pieces in the finished soup, do not return the cooked kelp to the pot. Most of the nutrition will remain in the stock.