Add all the dry ingredients for the batter in a bowl and mix well(flour, starch, garlic powder, salt, baking powder). Add the soy sauce, oil, and ⅓ cup water, and mix. Add water 1 tbsp at a time to make a thick smooth batter.
Add cauliflower florets to the bowl and toss to coat. Sprinkle panko aon the florets. Transfer to parchment-lined baking sheet.
Bake at 415 F(210 C) for 25-28 minutes. Check if the cauliflower is done at 25 mins. Remove from the oven when done and set aside
Heat oil in a large skillet over medium heat. Add the garlic, ginger, and chilis and stir. Cook until the garlic is golden ,2-3 minutes.
Add the onion, bell pepper, and celery and cook until golden . 8 minutes.
Add in the sauces. The Asian chili sauce, soy sauce, ketchup, vinegar, black pepper, and sugar and bring it to a boil.
Mix together corn starch in ½ cup of water then add it to the skillet. Cook until the sauce comes to a good boil and thickens. Taste and adjust seasoning. Adjusting the soy sauce for salt and heat with black pepper or Asian Chili Sauce.
Once thickened, cool for 5 mins, then add your baked cauliflower and toss to coat. Top with green onions and serve immediately. See notes for storage
