Press tofu using a tofu press or the tried and true method of two cutting boards and a stack of books. You can skip pressing it, but it does make for a better texture. Once pressed, cut the tofu into small pieces, roughly 1/2"x1/2" cubes. Bring the 6 cups water, salt, nutritional yeast, and sage to a boil. Gently stir in the tofu, let simmer for 10-20 minutes. This step takes place while you're prepping other ingredients. *You can skip this step of pre-cooking the tofu and just add the tofu cubes into the soup. However, I enjoy the results of this step because it gives the tofu a flavor.
In a separate pot, heat the oil for one minute over medium high then add the onion. Stir and cook for 3 minutes or until the onion is translucent. Add in the celery, carrot, and garlic. Cook for 3 minutes.
Add potato, corn, peas, vegetable stock, pepper, sage, and salt. Bring to a boil, reduce to simmer, cover and cook for 10-15 minutes or until the carrot and potatoes are softened. Add the cooked and drained tofu.
While the prior step is cooking complete this step. In a large measuring cup mix together the milk, nutritional yeast, miso, and corn starch. Pour into soup, gently stir in, bring to a light boil, then take off heat.
Serve with fresh sprigs of herbs like thyme, oregano, chives, or microgreens. Or just eat it.