Turn the Instant Pot to the sauté setting and add the olive oil and garlic. Sauté for 1 minute.
While the garlic sautés, mix the broth, mustard, salt, pepper and vinegar in a bowl until smooth.
Add to the Instant Pot along with the cauliflower and mix so the cauliflower is coated.
Pressure cook on high for 3 minutes and use the quick release to release the pressure when done. Serve hot.
Notes
Make sure to cut the cauliflower into roughly equal pieces so it cooks evenly.
If you like your cauliflower on the firmer side, reduce the pressure cooking time by 1 minute, or cut it into larger florets.
Be sure to do a quick release of the pressure. If you naturally release the pressure, the cauliflower will continue cooking and will be overcooked and mushy.
The recipe can easily be double without changing the cook time.