1. To make the cauliflower rice, you can either grate the cauliflower on a box grater to form rice-like grains, or you can process it in two batches in your food processor, pulsing with the S blade till it resembles rice. When you're finished, transfer the rice to a large mixing bowl.
2. Add the olives, tomatoes, capers, lemon juice, oil, and oregano. Give everything a toss.
3. Serve, garnished with some fresh chives, if desired.