German Sauerkraut

German sauerkraut, lacto-fermented with about 2% salt over several weeks, is one of the West's oldest fermented probiotic foods, producing a genomically diverse mix of lactic acid bacteria. At around 27 kilocalories per cup and pennies per serving when home-fermented, it's a cheap way to get fermented probiotics, while preserving vitamin C and offering compounds like GABA that raw cabbage doesn't.