Trim the outer leaves from the cabbage and cut the cabbage into quarters. Take out the hard stalks and shred the cabbage finely. Pack the cabbage into a large barrel or crock with salt and apples. Do this by putting in a layer of cabbage about 4 in/10 cm. deep and sprinkling with 3 oz/75 g salt and 1 finely chopped apple. Press down the layers and continue, pressing and pounding very thoroughly so that moisture is released and the cabbage becomes covered with brine. Fill the crock, but leave enough space for the cabbage to swell and ferment without overflowing. Cover with a layer of whole cabbage leaves and a thick layer of salt. Put on a clean cloth and a piece of wood which fits into the top of the crock, and put a heavy weight on top. Keep in a warm place to ferment. After two weeks the level of liquid will have risen considerably. Skim off scum and replace with a fresh cloth. Wash the lid and sides of the crock and replace the lid and weight. Put in a cool place for storage. Put on a clean cloth, and wash the lid and crock every week. The sauerkraut is ready for use in 3–4 weeks when fermentation has ceased.
If sauerkraut is not to be used as soon as it is ready, the juice should be drained off and heated to boiling point. Add the shreds of cabbage and bring to simmering point, then pack at once into heated preserving jars. Adjust the lids and process in boiling water for 25 minutes. Take out the jars, tighten the lids and cool before storage.