Start by adding the rice and water to a saucepan and bringing it to a boil. Once boiling, reduce the heat, cover the pot, and let the rice simmer until the liquid is absorbed. This usually takes about 20 minutes and creates soft, fluffy rice.
In a small bowl, mix sugar and rice vinegar, then stir it into the cooked rice. Fluff the rice gently with a fork and let it cool slightly so it holds its shape when stacking.
The batter should be thick enough to coat the cauliflower but still slightly runny. If needed, add a little more milk to adjust the consistency.
Dip each cauliflower floret into the batter and let the excess drip off. Place the coated florets on the prepared baking sheet in a single layer.
Bake for about 25 minutes, flipping halfway through so they cook evenly. The cauliflower should become golden and slightly crispy.
Remove the cauliflower from the oven and pour the teriyaki sauce over the roasted pieces. Toss everything gently so the sauce coats each floret evenly.
Return the pan to the oven and bake for another 5 minutes. Toss again and bake for 2–5 more minutes, keeping an eye on it so the sauce doesn’t burn.
While the cauliflower is roasting, prepare the avocado layer. In a bowl, combine diced avocado, chopped cilantro, and lime juice.
Mix gently so the avocado stays chunky but well coated with the citrus and herbs.
Lightly spray a measuring cup with oil to prevent sticking. Add a layer of avocado mixture at the bottom of the cup, then fill the rest with sticky rice.
Press the rice down firmly and run a knife around the edge. Flip the cup onto a plate and gently tap until the stack slides out.
Place a couple pieces of teriyaki cauliflower on top of each rice stack. Drizzle spicy mayo over the top and sprinkle with cilantro and sesame seeds.
Serve immediately while the cauliflower is still crispy and warm for the best flavor and texture.