Stir-fry the pork belly in a large, deep wok with 1 tablespoon of vegetable oil for about 4-5 minutes, until golden brown and crispy.
Pour out the excess pork fat. Add radish and stir fry for 1 minute.
Add potato, onion, and zucchini and keep stirring for about 3 minutes until the potato looks a little translucent.
Clear a space in the center of the wok by pushing the ingredients to the edges.
Add 2 tablespoons of vegetable oil to the center of the wok, then add ¼ cup of black bean paste and stir it with a wooden spoon for 1 minute to fry it.
Then mix everything in the wok and keep stirring.
Add 2 cups of water to the wok and let it cook with the lid closed for about 10 minutes.
Open the lid and taste a sample of the radish and potato. If they're fully cooked, stir in the starch water little by little.
Keep stirring until it's well mixed and thick. Add the sesame oil and remove from the heat.
Boil and drain the noodles. Rinse and strain in cold water.
Put one serving of noodles onto a serving plate and add the jjajang sauce over top.
Garnish with cucumber strips and serve immediately with kimchi or yellow pickled radish.
Notes
Substitutions for Radish
Best
Turnip – closest in texture and mild flavor
Kohlrabi – slightly sweeter, holds its shape well
Chinese napa cabbage stems (the white crunchy parts) – softer but works in a pinch
Acceptable but different
Extra zucchini – softer, less crunch
Carrot – sweeter and firmer; use a bit less so it doesn’t dominate
Substitutions for Potato Starch
Best
Cornstarch (1:1 replacement)
→ Mix 2 tbsp cornstarch with ¼ cup water + sugar, same as the recipe
Sweet potato starch (also 1:1)
Other options
Tapioca starch – slightly chewier, very glossy
Arrowroot powder – clean flavor, but thickens at lower heat (don’t overboil)
