1 head of red cabbage
2-3 tablespoons salt (I use basic kosher salt)
water to fill your container
Non-rusting container large enough to hold a head of chopped cabbage
A clean smooth rock to hold the cabbage under the water line
You could use a glass or a saucer, anything handy. I boil any stones I use.
Just layer the salt and cabbage until you fill the container or run out of cabbage. Try to pack it down and gently tap the jar on the counter to get as much air out as possible when you add water. Top it off with water so it covers the cabbage. I use a stone, drinking glass or saucer to hold the cabbage under the surface of the water, again this is important to keep the cabbage away from air and in the brine. That's it. Now set it some place warm(ish) 45 to 65 degrees seems to work well for me. Any colder and it won't ferment, warmer and it tends to rot. Though, using more than typical salt I don't seem to have that issue too often. Give it between a week and a month tasting as it goes. When you like how it tastes remove the stone or whatever is holding down the cabbage turned sauerkraut and refrigerate or eat within a day or two. I have managed to keep it in the refrigerator for about a month but it usually gets eaten before it has a chance to go bad.
You can add dill, mustard seed, caraway, fennel or anything else you might want. I just like it simple. It's very adaptive and can be used in everything from soup and stew to the expected brats and hot dogs. I've even topped mashed root vegetables with it!
If you are interested in more fermentation projects you might check out the Wild Fermentation site. My recipe is saltier and a much smaller batch than the one offered on the site but there are lots of ways to go about this and lots of fun things to try fermenting.