Preheat the oven to 450°F (232°C). Line a large baking tray with parchment paper and spray with a light coating of cooking spray.
Combine the Chinkiang vinegar, Shaoxing wine, soy sauce, sugar, and cornstarch in a medium-sized bowl. Stir to dissolve the sugar and cornstarch.
Dry the cauliflower thoroughly with paper towels. Add the cauliflower florets to a large bowl. Drizzle with oil and toss a few times. Add the flour and toss until the the florets are coated. Pour in the milk and toss again. Add the cornstarch and toss until the cauliflower is evenly coated. Spread the coated cauliflower on to the lined baking tray, making sure the pieces are evenly spaced out with gaps in between (*Footnote 2). Bake for 25 minutes in total. Check the cauliflower at the 15- and 20-minute marks. If the bottom is browned, flip the cauliflower. Once the baking is finished, the cauliflower should turn golden brown spotly and crispy throughout.
While the cauliflower is baking, make the sauce. Add the oil, peppercorns, and dried chilis to a small saucepan and turn the heat to medium-low. Once they become fragrant, about 1 minute, add the ginger and garlic. Cook until they are just starting to brown, another 1 to 2 minutes. Stir the sauce again to re-dissolve the cornstarch completely and add it to the pan. Raise the heat to medium-high and bring it to a boil. Boil until the sauce is just thickened. Remove the pot from the heat and set it aside.
After the cauliflower has baked for 25 minutes, pull the tray out and turn the heat to 500°F. Add the peanuts, peppers, and green onions. Put the tray back in the oven and cook for another 5 minutes, until the peppers are lightly cooked.
Pour the sauce over the cauliflower and gently toss to coat (*Footnote 3). Serve immediately as a side or a main.
It’s important to cut the cauliflower to the right size to ensure even roasting and browning. See the blog post above to see how to cut the cauliflower.
It’s very important to leave some space between the cauliflower florets, so the cauliflower will release steam and turn crispy once baked. If your baking tray does not have enough space, bake the rest in a separate tray. You can bake both trays at the same time by place the smaller tray on a different rack.
If you’re not serving the dish immediately, let the cauliflower cool off for a bit before tossing in the sauce. The cauliflower will stay crispy better this way.