Cut lemons lengthwise into quarters from the top to within 1/2 inch of bottom, without separating quarters.
Sprinkle 1 tablespoon of salt into a clean 1-quart jar; pack lemons into jar. Cover with lid, and shake; freeze 8 hours.
Sprinkle lemons with remaining 4 tablespoons salt; cover with lid, and shake to coat. Remove lid, and press lemons to release juices. Add 1/2 cup lemon juice to cover lemons. Cover with lid; refrigerate 6 days, shaking jar each day. Store in refrigerator up to 6 months.
Note: Preserved lemons may have a white film; rinse under cold water prior to using. The quarters can be used with or without pulp. Lemons will darken during storage.