Wash the lemons well and cut each into six to eight wedges. Press a generous amount of sea salt into the cut surfaces, pushing it into every crevice.
Pack the salted lemon wedges into 5 cup sterilized jars. To each jar, add 2-3 tbsp salt and 6 tbsp lemon juice, then top with boiling water to cover the lemons. (If using larger jars, use more lemon juice and less water)
Cover the jars and leave to stand for 2-4 weeks before serving.
To serve, rinse the preserved lemons well to remove some of the salty flavor, then pulled off and discard the flesh. Cut the lemon peel into strips or leave in chunks and use as you like.