Cut the cabbage(s) length-ways into quarters.
Don't chop the dead end of the root off,. You'll need it to keep the cabbage together. Instead, cut part way up in half, the cabbage should tear apart easily (and save the leaves). Repeat for each half to make quarters.
Wash the cabbage in salt water.
Grab a large bowl and pour half of the cup of the Korean sea salt in. Add water and let it dissolve. Using a quarter at a time, wash the leaves. Remove excess water and transfer to another bowl. Keep the salt water!
Mix the remaining salt with the garlic salt and sprinkle generously over the cabbage quarters, paying attention to the white parts. Once coated, cover with the remaining salt water.
No, seriously. Leave that baby to rest for a day. Yes, 6-8 hours. Rotate the cabbages so they get equally soaked. It's ready when those stiff white parts (snigger) are no longer stiff.
Prepare the seasoning.
While the cabbage is resting, you can start making the seasoning.
You're using chili here. Either use gloves, or make sure you're paying attention to where your fingers are going because it will burn!
Bring half a cup of water to a simmer and add the rice powder. Stir until it thickens then allow to cool. Once cool, add red chili pepper flakes, salted shrimp (finely minced), raw shrimp (finely minced), fish sauce, minced garlic, grated ginger, and water.
Chop up your Korean radish and scallions into thin slices.
Combine it all together.
Here's where the tasting comes in. According to halmeoni, it needs to be too salty to eat... so add more salt if you need...
Start by chopping off most of the root stem. You need just enough to keep the cabbage together. Smooth over each leaf.
Either eat or store!
It's OK to eat the kimchi now. However, kimchi tastes better the longer you leave it. Ideally, it needs two weeks for the flavor to fully develop
So, if you can, put it in a jar or airtight container. Add a little extra water. Leave it in room temperature then after a day, add to the refrigerator.
Once you're ready to eat, chop into bite-sized, starting at the tip.