At least two hours before you start cooking, bring the water to boil with the shitake mushrooms and kombu In a pot. Turn off the cooker and set aside.
In another pot (if you don't have another pot, transfer the Umami broth to a ceramic bowl and use the same one), heat the oil and cook the red pepper, mushrooms and carrot until soft on a medium heat. Add in the onion and ginger and continue cooking for about 2 minutes.
Add in the potato, sweet potato, brussels sprouts, edamame beans and garlic puree and carry on cooking for a minute.
Pour in the Umami broth and vegetable stock and cook on a low heat until the potatoes are soft.
Add in the spring onion and miso paste and stir slowly to dissolve the miso paste. Season with salt and black pepper as needed.
Leave to simmer for about 10 minutes. Taste your soup and if you want the flavour to be a little stronger, add a bit more miso.
You can take out the shitake and kombu and discard if you wish at this point before serving but I recommend to leave them as they continue to release the umami juice. We eat the shitake as they become softer in the soup, they are delicious!