Cut the onion, pork, zucchini, and potato into bite-sized pieces.
Heat cooking oil in a pan and stir-fry the pork.
When the pork is cooked, add the onion, zucchini, and potato, and stir-fry together.
Add the black bean paste (chunjang) and mix well while stir-frying.
Add water and dissolved potato starch to thicken the sauce.
Put rice on a plate and pour the jajang sauce over the top.