Step 1

Preheat oven to 400°. Whisk flour, cornstarch, baking powder, and salt in a large bowl to combine. Whisk in 1 cup water to create a thin pancake-like batter (you may need to add more water to achieve the right consistency). Using your hand or 2 forks and working one at a time, dip cauliflower florets into batter, letting excess drip back into bowl, and divide between 2 parchment-lined rimmed baking sheets. Bake cauliflower until edges are just beginning to turn golden brown, 20–25 minutes.

Step 2

Meanwhile, whisk gochujang, soy sauce, maple syrup, mirin, and 1 cup water in a medium bowl. Pour sauce into a skillet large enough to hold all of the cauliflower florets (a 12" skillet should do it) and bring to a simmer over medium heat, whisking occasionally. Cook, whisking, until sauce is thick enough to coat a spoon, 8–10 minutes. Stir in vinegar and remove pan from heat.

Step 3

Using tongs, transfer cauliflower to skillet with glaze and toss until florets are evenly coated in sauce.

Step 4

Divide rice among shallow bowls and spoon cauliflower over. Top with sesame seeds and scallions.