Dice onion, pork, potato, and zucchini.
Add cooking oil to a pan and stir-fry the pork.
Add onion, potato, and zucchini, then stir-fry together.
Add black bean paste and stir-fry with the ingredients.
Pour in water and add sugar, then bring to a boil.
Simmer over medium heat until the potatoes are cooked.
Add starch water to adjust the thickness.
Serve the jajang sauce over noodles and finish.