1. Remove one or two outer leaves of your cabbage and set aside.
2. Thinly shred your cabbage, discarding the core when you come to it.
3. Give it a good rinse. Shake dry. Pop it into a big bowl.
4. Dust 1 heaped tbsp sea salt over. Add your spice, if using, too. Let it sit for 30 mins-1 hr to help draw out some of the moisture.
5. Then, get your hands stuck in there and massage and scrunch it till you get a good bit of liquid (at least 1/2 mug full) coming out. This will take 5-10 mins.
6. Pack the juicy cabbage into a sterilised jar (wash with boiling hot, soapy water and dry in a 160C/gas 3 oven for 10 mins). Add the kraut little by little, packing down each layer as you go. Key is to ensure you keep as much air out as possible.
7. Use the reserved cabbage leaves to cover the compacted cabbage. Press down till there's a good layer of liquid (the brine created using the juices from the cabbage and the salt - this is what kickstarts the fermentation) covering it. Place a heavy object on top like a full jam jar or some clean stones to help weight it down - you can use a ziplock back to help.
8. Pop a lid on it and keep it air tight. Open it once a day to release any building gasses and check your kraut to ensure it's still covered with liquid. If not, sprinkle a dusting of salt over the top (about 1/4 tsp) and pour over enough filtered or mineral water to cover the mix by 1-2cm.
9. Keep in a dry spot at room temperature for 5-7 days. Check daily to ensure the liquid is always covering the cabbage and that none of the cabbage is exposed to air.
10. After 5-7 days it should smell and taste like sauerkraut. Get stuck in. So long as it's fully covered in the brining liquid it'll keep for months in the fridge. Any time it looks or smells off, discard it. Otherwise, you're good to go. Let it ferment until the tang and tenderness is to your liking. The longer it ferments the more vinegary it will taste, and the softer the cabbage will become. You can ferment it for 2 weeks or more if you like but around 7 days is ideal for most. Once you're happy with it, pop it in the fridge to stop it fermenting further. Ensure it's sorted air tight and still covered with a layer of brine. Doing this means it will keep for months. If you have a lot of kraut, you can always decant it into smaller, sterlised jars - again ensuring it's air tight and covered wtih a layer of brine.