Place the minced ginger and garlic into the Instant Pot liner along with the shitake mushrooms, rice, and water. Stir.
Seal the Instant Pot and press the "porridge" button - this should set for 20 minutes of cooking at high pressure. You can use the manual button if you prefer.
While the Pot is coming to pressure and cooking, chop the carrot and zucchini and set aside. Then prepare your toppings.
Allow the Instant Pot a natural pressure release, otherwise you will spray your kitchen with porridge and clog the vent. Ugh. This should take about 10 minutes.
When the pressure has released, unseal the lid and quickly tip in the chopped carrot and zucchini. Stir it around and then put the lid back on. Wait a minute or two, and then go ahead and serve; the veggies will have softened enough by then.
Add your toppings and eat!