Buy a container of cabbage kimchi.
You can buy whole or pre-cut cabbage kimchi.
You can use kimchi that you made and that has been fermenting in the fridge.
Place the container in a cool, dark area with no direct sunlight. If it is in a clear container, cover it with a cloth.
Do not place it near sunlight or warm areas like the window.
Leave it there for 3 days.
After three days, put it back in the fridge.
It will now have a sour flavor and can be used for cooking.
Make sure you keep the kimchi in the fridge after three days. Do not just leave it on your counter forever.