Wash the cauliflower and remove the outer leaves. If you find any black spots, remove them with a paring knife.
Cut the cauliflower in half (vertically), and use a chef's knife to remove the core and leaves.
Cut each half into larger pieces.
Using the edge of the cheese grater with large holes, run each wedge of cauliflower over the cerated edges. Repeat with the remaining cauliflower pieces.
If not cooking immediately, refrigerate the cauliflower rice in an airtight container for up to 3 days.