Instant Pot: Put all the ingredients in the first list into the Instant Pot (affiliate link). Cook for 45 minutes (manual). Release steam using the valve on top. Stovetop: When the soup is done, melt the butter in a saucepan. Whisk in the flour. Let the mixture cook for a minute or two to remove the floury taste. Whisk the milk, a little bit at a time, until you have a smooth, thickened sauce. Throw a little salt in there for good measure. Together: Mix the creamy sauce with the soup in the instant pot. Voila! Mushroom Wild Rice Soup.