Combine the cabbage, apples, ginger, and salt in a large bowl and rub them together until you have a goodly amount of liquid in the bowl. Or let them sit until soft and liquidy.
Pack the wilted veg into a crock or a wide mouth jar that can hold at least a half gallon a handful at a time. Press each layer down firmly. If you push it all in at once, you won't get it all in.
Once you have all the veg into the jar, weigh it down with pickling weights. If you don't have pickling weights, find a small jar that can fit inside your jar or use a plastic ziptop bag filled with water.
Set the crock/jar on a plate. Cover it and place it somewhere that's out of direct sunlight.
Check the kraut every couple of days and push it back down if it expands.
When it tastes tangy and good, it's done! This can take anywhere from 10 days to three weeks. Put it into the fridge and enjoy.