Preheat your oven to 425°F and line a baking sheet with parchment paper.

In a large bowl, whisk together flour, cornstarch, salt, and black pepper. Gradually whisk in 3/4 cup water until you have a smooth batter.

Add the cauliflower to the batter, toss to coat, and spread the florets on the prepared baking sheet in a single layer.

Bake the cauliflower for 25 minutes, turning halfway, until golden and crispy.

Meanwhile, whisk together soy sauce, hoisin sauce, rice vinegar, brown sugar, 1 tablespoon cornstarch, and 1/4 cup water in a small bowl and set aside.

Heat vegetable oil in a large skillet over medium heat. Add minced garlic, grated ginger, and sliced chili pepper. Cook until fragrant, about 1 minute.

Pour the sauce into the skillet, bring to a simmer, and cook until thickened, about 2 minutes.

Add the roasted cauliflower to the skillet, toss to coat, and heat through.

Divide the cooked rice among bowls, top with sauced cauliflower, and garnish with sliced green onions and sesame seeds.