Cut off the end and leaves of the cauliflower. Wash and thoroughly dry*.
Break the cauliflower into florets or cut into smaller pieces. Pulse in a food processor on low until cauliflower turns into "rice" **.
Optional: Transfer cauliflower rice to a paper towel and press to remove extra moisture.
Notes
*To wash the cauliflower, I usually break them into florets and soak in water and apple cider vinegar or vegetable wash (Apple Cider Vinegar help reduce pesticides). Then rinse off the cauliflower thoroughly.
** Do not blend on high. You want the "rice" texture instead of a mashed one.