In a small bowl, mix together 1 tablespoon cornstarch with a pinch each of salt, pepper, and baking powder. Sprinkle cauliflower florets with the mixture and stir to coat.
In a large bowl, whisk together the flour, cornstarch, baking powder, and garlic powder for the batter. Then add the cold water. The batter will be on the thick side, kind of like pancake batter.
Dip the cauliflower into the batter to coat, shake a little over the bowl to allow excess batter drip off, then place the coated cauliflower on a wire rack (with a paper towel underneath) to allow more excess batter to drip off. Better for excess to drip off before it goes into the air fryer.
Brush the air fryer basket with a light layer of oil to help reduce sticking. Place coated cauliflower into the air fryer basket in a single layer, with space between each floret. Cook at 350˚F/177˚C for 10-12 minutes, until parts are light golden brown. (For my air fryer, this took 4 batches to cook all cauliflower. Remove debris and re-coat basket with oil between each batch.)
While the cauliflower is cooking, you can finish dipping the remaining cauliflower florets, then work on the sauce. Whisk together the gochujang, soy sauce, honey, sesame oil, ginger, garlic, and vinegar in a small saucepan. Bring to a simmer over medium heat, then remove from heat.
Once cauliflower is done cooking, add it to a large bowl. Then pour the sauce over the cauliflower and gently stir to coat.
Serve immediately. If desired, garnish with lime zest, lime wedges, green onion, and sesame seeds. Delicious served with a side of Ranch dressing.
Sauce can be mixed together up to 3 days in advance. Cover and refrigerate it, then bring to a simmer right before serving.Cook time may vary and will depend on how many batches it takes for you to air fry the cauliflower florets.