Preheat oven to 425°F, and line two baking sheets with parchment paper.
Rinse rice, and add it to a pressure cooker with equal parts water. Set the time according to your pressure cooker instructions. Note: if you are using a rice cooker, double the amount of water to rice.
Chop cauliflower into bite-size pieces. Then, toss cauliflower florets in oil, salt, and pepper. Once coated, coat florets in corn starch.
Spread cauliflower evenly out on the two parchment-lined pans. Bake at 425°F for 20-25 minutes, or until turning brown. Make sure to flip halfway.
While cauliflower is baking, whisk together sweet & sour sauce ingredients in a bowl. Add everything to a saucepan, and simmer on low for 5-6 minutes, or until it's starting to thicken.
Once the cauliflower is done, toss each floret in sweet & sour sauce.
Serve cauliflower over rice and top with green onions, cilantro, and sesame seeds.