Turn on the Saute function of the Instant Pot.
Add the butter and once it's melted, add the carrots, celery, onion, and mushrooms.
Stir to coat all of the vegetables with the melted butter.
Cook the vegetables for 5 minutes, or until the vegetables are tender and have started to brown.
Add in the garlic and sage and cook for another minute.
Add in the chicken stock, turkey, noodles, salt, pepper, and bay leaf, and give it a stir.
Attach the lid and make sure the valve is in the sealing position.
Choose Manual, High Pressure and set it for 3 minutes.
When it's done cooking, do a manual release by switching the valve to the venting position. Be careful!
Remove the bay leaf and add more salt and pepper, to taste. Serve warm.
Refrigerate leftover soup in an airtight container in the fridge for up to three days.