Preheat the Instant Pot on sauté setting (regular), and add oil to the pot.
After about a minute, add the onion and mushrooms, and cook for about 4 minutes, stirring frequently.
Add the garlic, and cook 30 seconds more.
Add the rice, and toast for 2 to 3 minutes, stirring constantly.
Turn off the heat, add the water and Better Than Bullion vegetable base, and scrape to remove any rice that stuck to the bottom or sides.
Place the lid on, lock it, and cook at high manual pressure for 20 minutes, and allow the pot to NPR.
Once the pressure has released, turn off the pot (so rice doesn't scorch), remove the lid, fluff with a fork, and taste to see if you need to add salt. This will largely depend on how salty your stock/ broth was.
Add (optional) chopped fresh parsley for garnish, and serve immediately.
I am using a raw rice mix for this recipe. If yours is parboiled (check the label!) it will need significantly less cooking time.