Equipment Needed: Large mixing bowl 2 pint-sized glass canning jars 2 coffee filters or 6-inch square pieces of cheesecloth 2 glass jar rings or rubber bands 1. Make sure your mixing bowl and the jars are very clean. 2. Strip away the outer leaves of the cabbage and discard. Cut cabbage into quarters, then cut out the white center core from each wedge. Cut the wedges crosswise into very thin slices. 3. Place the cabbage in the mixing bowl and sprinkle it with the salt. Massage the salt into the cabbage, gathering the cabbage in handfuls from the bottom of the bowl and constantly turning it over to make sure you massage all of the cabbage. Massage the cabbage for 5 to 10 minutes or until the cabbage looks more like coleslaw and has shrunk by about half. (It will continue to become more and more watery.) Add the mustard seeds and massage for another few seconds. 4. Fill the jars with the cabbage, pressing the cabbage in firmly. As you pack the cabbage into the jars, water from the cabbage will rise up to the top. Once all the cabbage has been added to the jars, pour any remaining water in the mixing bowl into the jars. Press down on the cabbage, if necessary to make sure it’s completely submerged in the water. Place 1 coffee filter over the top of each jar; secure it by lightly screwing on the glass jar ring. 5. Let the jars of cabbage stand at a cool room temp (between 65° and 75°) out of direct sunlight to ferment. 6. Over the course of the next 24 hours, using the back of a spoon, continue pressing down on the cabbage to keep it submerged in the water. If the cabbage isn’t fully submerged after 24 hours, dissolve 1 teaspoon of salt in 1 cup of water; add enough of the salt water to jars so cabbage is submerged. 7. After 5 days, the cabbage should start to take on a tangy flavor. If white scum or foam forms on top of the cabbage as it’s fermenting, that’s fine, it’s just a sign of the fermentation process at work. Bubbles are also a natural result of fermentation. If mold appears, scoop it off and discard any cabbage that was in contact with it. 8. Over the next several days, continue to taste the cabbage and make sure it remains submerged in the water. Once the cabbage is to your liking (which could take up to the 10th day) secure the jars with lids and refrigerate for up to 2 months.