Can I use a whole head of cauliflower?

Yes—use the same technique but increase cooking time slightly and work in batches if needed so the pan remains in a single layer. Watch for doneness: larger pieces will need a minute or two more.

Is peanut oil required?

No. Peanut oil is used for its high smoke point and neutral flavor, but canola, vegetable, or avocado oil are suitable high-heat substitutes.

How do I get the cauliflower to brown instead of steam?

Use a large pan so pieces sit in a single layer, heat the oil until shimmering, and stir only occasionally to allow contact with the hot pan—this encourages browning rather than steaming.