In your Instant Pot, press the saute button and saute onions and garlic in oil for 3 minutes. Add the carrots, celery, and mushrooms. Saute for 4 minutes. Add the salt, thyme, sage, and black pepper. Saute for 30 seconds more. Then add the rice and saute for 1 minute. Turn Instant Pot off and add the vegetable broth. Stir until everything is combined. Add the bay leaves.
Lock the lid of the Instant Pot and make sure the pressure release valve is in the “sealing” position. Cook on high for 35 minutes. Once done, do a quick release. I usually place a damp towel on the valve so it doesn’t spray everywhere.
Remove the bay leaves. Remove a small amount of broth from the soup and add it to a small bowl. Stir in the tapioca starch or cornstarch in the small bowl with the broth until smooth and add it back into the pot. Stir the soup continuously until it thickens up. It will thicken up more as it cools a little. Add the soy sauce and stir. Add extra salt (I added another 1/4 tsp) and pepper if needed. Enjoy!
If making this on the stove top, simmer the soup for 30-40 minutes or until rice is cooked through after adding the bay leaves.