01 - Preheat oven to 425°F. Line a large baking sheet with parchment paper.
02 - In a large mixing bowl, whisk together flour, cornstarch, garlic powder, smoked paprika, salt, and black pepper until evenly combined.
03 - Add milk to dry mixture and whisk until a smooth, thick batter forms.
04 - Add cauliflower florets to the batter and toss to coat each piece thoroughly.
05 - Transfer battered cauliflower to the prepared baking sheet in a single layer. Drizzle lightly with olive oil.
06 - Roast for 25 to 30 minutes, turning halfway, until cauliflower is golden brown and crisp.
07 - While cauliflower is roasting, whisk together mayonnaise, sweet chili sauce, Sriracha, honey or maple syrup, rice vinegar, and a pinch of salt in a small bowl until smooth.
08 - When roasted, transfer cauliflower to a large bowl. Add Bang Bang Sauce and toss gently until evenly coated.
09 - Arrange sauced cauliflower on a serving platter. Garnish with chopped scallions and sesame seeds if desired. Serve immediately.