When you're ready to eat, preheat your deep fryer to 180° C/ 360° F.
In a bowl, whisk together the 1/2 c - 60 gr of cornstarch and flour, 1/2 t - 2.5 gr of baking powder, 1 t - 5 gr of salt, 1/2 c - 125 ml soju and cold water until just smooth.
Remove the chicken from the milk and pat dry with a kitchen towel.
Now set up your fry station: chicken, batter, kitchen towel lined plate or tray.
Check to see if your oil is up to temperature by dumping a tiny bit of batter into the oil. When the batter sizzles and floats to the top you're good to go.
Dip the chicken into the batter, shake off any excess and gently lower it into the fat. Don't use a wire bask or skimmer at this point as the batter will immediately crisp up and get stuck. You'll want to carefully lower it into the fat with tongs or a fork so you can let go before the last corner hits the fat. Depending on the size of your fryer you can fry about 2-3 pieces at a time. Avoid overcrowding the pan.
Fry until the batter is golden and crisp and the chicken is cooked through. This will take 7-10 minutes, depending on the size and thickness of your chicken.
While the chicken is frying, mix together your 1/2 c - 60 gr of gochujang with 5 t - 25 gr of Frank's OR 5 t - 25 gr of mirin, depending on your heat resistance, and place at the end of the line of your fry station.
As you move chicken from the fryer let it sit on the paper towels to remove any excess oil and then, while still hot, toss in the hot sauce for a nice glaze.