Instant Pot Method: Core the cauliflower and cut the florets into 3 to 4 large sections. Pour 1 cup of water into the Instant Pot and place the large cauliflower pieces inside. Lock the lid, then turn the steam knob to the " sealed" setting. Press the vegetable steam button. Once complete, transfer the steamed cauliflower to a colander to drain, then set on a paper towel and pat dry. Complete from Step 3 above to make the mash.