How to Make It
In a blender, combine the gochujang with the sugar, garlic and mirin. Add 1 cup of water and blend until smooth. Add the yuzu kosho and 1 cup of water and pulse to combine. Transfer the mixture to a medium saucepan and bring to a boil. Simmer over moderate heat, stirring occasionally, until the sauce is reduced to 1 1/2 cups, about 15 minutes. Transfer the gochujang sauce to a large bowl and let cool.
Meanwhile, in a large bowl, whisk the tempura flour with the egg yolk and 1 cup of ice water until smooth. Add the wheat flour, potato starch and 1 cup plus 2 tablespoons of ice water and whisk until smooth; the consistency should be that of thin pancake batter. Add the cauliflower, stirring to coat.
In a large saucepan, heat 2 inches of canola oil to 385°. Working in batches, lift the cauliflower florets from the batter, allowing the excess to drip back into the bowl. Fry the cauliflower, stirring occasionally, until the coating is golden and the florets are tender but not soft, 6 minutes. Drain the cauliflower on paper towels and immediately add to the sauce; toss to coat. Using a slotted spoon, transfer the cauliflower to a plate. Repeat with the remaining cauliflower. Serve each batch as it’s finished cooking. Sprinkle with sesame seeds and serve with lime wedges.
Gochujang is a spicy Korean chile pepper paste. Red yuzu kosho is a Japanese condiment made with yuzu, red chiles and salt. Tempura batter mix, such as Nisshin, is a combination of soft flours, usually containing wheat and corn. These ingredients are all available on amazon.com. Asian whole wheat flour, such as Yi Feng, is available at onlinefoodgrocery.com.