Pack the cabbage firmly into a very clean glass quart jar. Pour the liquid that was released during kneading on top. Cut a circle the same diameter as your jar out of the reserved cabbage leaf. Place it on top of the packed-down cabbage. Place a weight on top of the cabbage to ensure that it stays under the brine. If the brine doesn’t completely cover the cabbage and weight, top off with a 2% solution of salt water (1 teaspoon salt per cup of water).