I tasted this in Amsterdam in the Veganees, a shared dining restaurant based on Asian classics (1e Constantijn Huygenstraat 45, Amsterdam). The fried cauliflower in gochujang is basically the Korean restaurant classic yangnyeom-chikin.

You can substitute the chicken for cauliflower, I’m sure this will work. The recipe below is Maangchi's.

Ingredients:

One cauliflower, taken apart in florets.

For the batter:

½ teaspoon kosher salt
½ teaspoon ground black pepper
½ cup potato starch
¼ cup all purpose flour
½ teaspoon baking soda
2 large eggs (skip for a truly vegan version)
1 tablespoon toasted sesame seeds

For the sauce:

2 teaspoons vegetable oil
3 garlic cloves, minced
⅓ cup ketchup
⅓ cup rice syrup (skip for a less sweet version)
¼ cup gochujang (Korean hot pepper paste)
2 teaspoons white vinegar
2 teaspoons vegetable oil
corn (or vegetable) oil for frying

For a side dish, pickled radish (chicken-mu), optional

Fry the cauliflower florets coated in the batter in hot oil. Cool down. Mix the ingredients for the sauce on a medium heat. Fry the cauliflower florets for a second time until slightly crunchy. Coat the cauliflower in the sauce, mix well and sprinkle with sesame seeds.