Sauté the Base: Heat the olive oil in a large skillet or wok over medium-high heat. Add the onion and sauté for 3–4 minutes until soft. Stir in the garlic for 30 seconds until you can really smell it.
High-Heat Fry: Add the cauliflower rice to the pan. Turn the heat up slightly. Spread the rice out and let it "sear" for about 2 minutes without moving it—this creates a toasted flavor. Stir and cook for another 3 minutes. If using, add the ham.
The Savory Liquids: Pour in the soy sauce and the rice wine vinegar. Stir rapidly so the cauliflower absorbs the liquid evenly.
The Scramble: Push the rice to the sides of the pan. Pour the egg into the center. Let it sit for 30 seconds, then scramble it into small ribbons. Once cooked, fold the egg into the rice mixture. If using, add the garden peas and prawns. Make sure everything is cooked through.
The Finish: Turn off the heat. Drizzle the sesame oil over everything. Taste it first before adding salt and pepper, as the soy sauce is already quite salty.