Add the carrots, celery, onion, garlic, rice, mushrooms, chicken broth, salt, and poultry seasoning into the Instant Pot.
Lock lid in place and turn valve to sealing. Press Manual or Pressure Cook and set cook time for 45 minutes.
Allow natural release.
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. Add more salt if you need too.
Mix the creamy sauce with the soup in the Instant Pot and you will have DELICIOUS wild rice soup!
Notes
Instant Pot. If you don’t have and Instant Pot, you can buy one here! This isn’t one of the fancy models, but it works great and has a smaller price tag. We feel like a 6 quart is adequate, even for a family of 6, but you might consider an 8qt if you like to make bigger batches for plenty of leftovers.
Rice. I've seen lots of recipes that call for only wild rice, but using a wild rice blend is my favorite. But if you decide to use wild rice and not the "blend" you will still cook it for the same time.
To rinse or not rinse rice. We get a lot of questions with all of our Instant Pot rice recipes if we need to rinse the rice. I've done it both ways and I haven't seen a difference either way.
Stovetop. Unless you have another Instant pot, I would suggest using the stove top for the final step. 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. Mix the creamy sauce with the soup in the instant pot and you will have DELICIOUS wild rice soup!
Mushrooms. If you do not like mushrooms, you can leave them out. Add chicken instead (or in addition to mushrooms). Simply add the chicken with the rest of the ingredients, and shred it when it is done cooking. I also suggest chopping mushrooms into smaller pieces.