Cut the onion and pork into bite-sized pieces.
Heat oil in a pan and stir-fry the pork.
Add onion and vegetables, then stir-fry together.
Add chunjang (black bean paste) and stir while cooking.
Pour in water and add sugar, then bring to a boil.
Add starch water to adjust the thickness.
Spoon the finished jajang sauce over the cooked rice.