Add to the instant pot the carrots and garlic and continue the sauteing until the garlic has some colour to it. Cancel sauté, add the veggie stock (defrost it first) and stir and this will help deglaze the instant pot.
Add the frozen cauliflower and the frozen corn and stir. Place the lid on the instant pot, set the valve to sealing and pressure cook for 6 minutes followed by a quick pressure release.
After releasing pressure, use a wooden spoon to break down the cauliflower into small pieces – note that its okay that the cauliflower is mushy as this is the plan with this chowder.