Wash the cabbage well. Chop up into shreds. If you have a food processor you could use one of the attachments to make this step even easier.
Place the cabbage shreds into a large bowl and stir in the sea salt. Let stand for 15 minutes.
The cabbage now needs to be crushed to release the juice. You can do this by getting your hands into the cabbage and squeezing in between your fingers. It's probably easier to get something like the end of a rolling pin of meat tenderiser to break up the cabbage with.
Stir the caraway seeds in the cabbage mix.
Pack the cabbage shreds tightly into a jar. Here a special saurekraut pot is being used: https://www.amazon.co.uk/Original-Fermentation-Liter-Shape-weighting/dp/B00440YHSI/ref=as_sl_pc_as_ss_li_til?tag=wwwresultsall-21&linkCode=w00&linkId=57e2d9dacc44c3a5d2a699739a4124c9&creativeASIN=B00440YHSI.
Press all the air out and leave at least 2 inches of space below the lid, and more if you use one of the pots.
You may want to add a little brine (salt water) to the top to just cover the top of the cabbage with liquid. To make a brine use 1tsp salt to 1 pint of water.
Either put the lid on the jar or if you use the saurekraut pot you need to put in the two weights to compress the cabbage down before putting on the lid.
Place the jar in a dark corner of your kitchen for 1 week before putting into the fridge for a further 4 weeks.
After 4 weeks you may find a slight mould on the top of the cabbage on the bits not covered by liquid. Spoon them off and throw them away, the rest is good to be placed into glass jars and eaten with your meals.
The saurekraut can keep for months in the fridge.