To sterilise a glass jar, preheat oven to 120°C (250°F). Wash the jar and the (metal) lid in hot soapy water, rinse and place on a baking tray. Place in the oven for 20 minutes. Remove and allow to cool before filling.
If you prefer a stronger flavour, leave the cabbage fermenting at room temperature for a further 2 days.
The sauerkraut will keep for up to 1 month in the fridge.