Seems like every culture has it own spin on fermented cabbage. Sauerkraut, kimchee and curtido? On a recent trip to Central America I was fascinated by the cabbage relish served with regional pupusas and almost everything else. Seemingly every restaurant and food stall had a slightly different take on the recipe and were deservedly proud of their results.
The key is to brine the cabbage in a solution of 1 tablespoon of salt to 1 cup of water and half a cup of vinegar. Cover your thinly sliced cabbage with brine and leave the mixture on the counter to ferment naturally for a few days. You can eat it any time but it will mellow and become more complex over time. Put in the fridge after a few days.
You can add anything you like flavor-wise thinly sliced onions, carrots and oregano are traditional, garlic is always nice, peppers for heat. Oh right and the type of cabbage is not particularly important, but use red for its eye catching color.