Even though you can buy it, the best quality, most economical cauliflower rice is the kind you make yourself. I'll show you 2 easy methods for how to make cauliflower rice, with a grater and with a food processor.
Remove the green leaves and large stem using a paring knife. Trim any brown or bruised spots on the cauliflower.
Food Processor Method:
Cut the cauliflower into florets. Cut up or chop any stem pieces. Place in a food processor fitted with the steel chopping blade.
Pulse a few times to start breaking up the cauliflower florets. Continue pulsing until all of the florets are chopped. Stop and scrape down the sides, as needed, and remove any really large, hard pieces that aren't as easily chopped.
Grater Method:
Depending on the size desired, the larger holes or smaller holes can be used on the grater.
Keep the cauliflower intact, or cut in half, and start running the cauliflower firmly against the grater holes to create the rice.