In a stock pot, heat the ¼ cup of water over medium heat and add the onion,, celery, and garlic to the pot. Turn the heat to low and simmer the onions and celery until the onion is soft and translucent. Add the mushrooms and cook for another 3-5 minutes, adding more water if necessary.
When the mushrooms are tender, add the bouillon, kelp powder, pepper, thyme, potatoes, and vegetable stock. Stir well and bring to a simmer.
Meanwhile, whisk together the plant milk and all purpose flour. Add to the soup and cook until the potatoes are tender and the soup has thickened, or about 30 minutes.
Add more water if needed. Season the soup with sea salt and pepper to taste. Garnish with chopped parsley before serving.
Recipe by Plant Craft at https://www.rachelcarr.com/sea-vegetable-chowder/