Peel the hard, outer leaves off your cabbage. Cut the ends off and slice it in half.
Slice it into fine strips and place into a big mixing bowl. The narrower and smaller the slices, the quicker that your cabbage will ferment. You can use a mandolin to make this process easier.
Sprinkle salt over the cabbage. Use your hands to massage the salt well into the leaves. Squeeze and press it for at least 5 minutes, to draw out the water.
Leave the mixture for at least 30 minutes. The salt will draw even more water out of the cabbage.
Optional:Add your spices, additional veggies, seeds and berries.
Pour the mixture and brine into a Mason jar. Use your hands or a fermenting stomper to push the cabbage into the jar. The more pressure that you apply, the more water that will be squeezed out of the cabbage. This produces a salty brine.
Leave at least 5cm headspace at the top of your jar. Ensure that the cabbage is completely submerged under the salty brine. If you don't have enough brine to submerge it, you can leave the jar sitting on your bench for at least 20 minutes then try pushing the cabbage under the brine again. This will produce more salty brine. Alternatively, you can add a small quantity of extra brine by adding water and no more than 1/4 teaspoon of salt. Ensure that you do not oversalt your cabbage, or the taste will end up being unpleasant.
Place a glass weight or big cabbage leaves on top of the cabbage. This will keep it submerged under the brine (*** keeping your veggies under the brine is the most important part of creating a safe environment for fermentation***)
Place an airlock lid on top of your jar.
Put your jar in a cool, dry place for 2-4 weeks. Keep out of direct sunlight. The first 3 days of your fermentation will be the most active. Once it has settled, you can taste your sauerkraut every day. You can eat it when it tastes the way you like it. By leaving it for 2-4 weeks, you will get a better fermentation, with a richer flavour.
When you are happy with your sauerkraut, store it in your fridge. It is best to replace the airlock lid with a storage cap or canning lid.