Chop 8 oz of mushrooms into small bite-sized pieces.
Add 1 tbsp of oil and mushrooms to the pan with the salt and sauté the mushrooms at medium heat until they get darker and release their juices.
Add 4 cups of milk, 1 tsp salt, 1/2 tsp garlic powder, 1/4 tsp paprika, and 1/4 tsp black pepper.
Heat until the soup just barely begins to bubble then reduce the heat to low.
In a separate bowl, mix 1/4 cup potato or corn starch and 1 cup of water. Stir until it dissolves completely.
Pour the starch mixture into the hot soup stirring constantly.
Continue to heat the soup on low until it thickens and just starts to bubble.
Turn off heat and serve hot.
Notes
Potato starch gives it a slightly better texture and flavor than corn starch, but if you don't have it, corn starch will work well too.
If you are using thicker soy milk to make this, like Silk brand or equivalent, use 2 cups milk and 2 cups water.
You can also use unsweetened plant-based milk in this recipe.
Do not use vanilla-flavored plant milk.
You may also thicken this soup by adding 1/4 cup of oil and 1/4 cup of flour to the bottom of a second soup pot. Heat the flour and oil for a minute then slowly ladle in the hot broth stirring with a whisk between each scoop of liquid until all of the soup is added and it begins to bubble.
If using the method with oil and flour, still add the extra cup of water, just don't add the cornstarch.