Studies show that 80% of your immune system is in your gut. This is why the food you eat (or don't eat) is so important to your overall health. Eating whole, unprocessed foods without extra man-made additives helps maintain a healthy mix of microbes that enable your immune system to operate at its best. Fermented foods such as sauerkraut are a quick and easy way to feed those healthy microbes, but the fermented food need to be raw and unprocessed.
Sauerkraut is easy to make yourself, even in small quantities, and although it may be an acquired taste, it isn't at all bad tasting. All you need is a head of cabbage, some salt (preferable kosher or sea salt), a large bowl for mixing, a wide-mouthed Mason jar or other container, and something to use as a weight. I used half a head of cabbage, and one quart Mason jar was perfect. If using the whole head, you will need two jars or a larger container, and double the amount of salt.
Make sure your equipment is all squeaky clean (you don't want any bad bugs taking up residence). Shred the cabbage - I used a knife and a cutting board, but you could use a food processor if you like. Cut the head of cabbage into quarters, then cut each quarter into thirds. Trim off the core, then cut the wedge crosswise into fine shreds. Place in bowl and mix two teaspoons of salt into the cabbage, making sure all the cabbage is coated. Pack tightly into the Mason jar and add any liquid that may be left in the bowl. Cover the top of the cabbage with a piece of cabbage leaf, waxed paper or parchment paper, and then add a weight of some kind (I used a half-pint jar filled with water that fit inside the larger jar). The weight is to make sure the salted cabbage stays submerged in the liquid so that the top won't mold. (Check several hours after preparing to make sure it has formed enough liquid to cover all the cabbage. If not, add just enough water to cover). Cover with a cloth, and let sit at room temperature for at least 3 days. Pack the cabbage down firmly several times a day. After 3 days, taste it and if it is sour enough for your taste, move to the refrigerator. If you want it more sour, let it sit out longer.
A good forkful or two a day is all you need to gain the health benefits. It will keep indefinitely. My sauerkraut stayed a nice green color, and is crunchy, close to the texture of cole slaw. I just open the jar, take out a heaping forkful and eat it at least once a day.