I have looked over a lot fermenting blogs on how to ferment vegetables. There is a lot of use of whey, probiotic additives, kefir, and of course, just plain salting, in order to lacto-ferment vegetables. In Thailand, the tradition from Isaan (in the northeast, bordering with Laos) is to ferment vegetables by adding salt AND the starchy water that results from washing rice. I cannot find out exactly why this is added, other than it adds a really complex and delicious taste! Korean kimchi has a similar process of adding starch – either through rice flour paste, or potato (check out this site for great recipes!). I am assuming that by adding sugars (from the starch), you are giving yeasts something extra to feed on………
Thai-style lacto-fermenting results in a ferment that is 100% vegan, and a taste that totally trumps the traditional salting only method. You can buy it at most Isaan food stalls here across Thailand, and its called Pak Dong in Thai. The usual vegetables added are mustard leaf stems and spring onions and sometimes whole chillis. You can use cabbage, in fact any firm stemmed leafy green vegetable would suffice, but the mustard green stems really are best for flavour – you get a slight tang of horseradish along with sour saltiness when you eat it.
So by using this method, you could ferment any kind of vegetable. I have only tried with cabbage, chillis, onions and shredded green mango, all of which were delicious. Some side-by-side testing wouldn’t go amiss, between (1) original salting, (2) adding rice water, and (3) adding whey.
The directions are very simple:
Cut most of the green leaves off a bunch of mustard. Cut the stems into pieces, as big as you would want to eat. Wash and leave them in direct sun for a few hours to wilt and dry slightly. Then massage them with salt (to taste) until they are quite bruised and juices are coming out. Don’t be shy, you really need to use your muscles here if the stems are meaty. If you want to add spring onions, add towards the end of the massage as they will break down easier. Press them down to submerge as much as possible, and then leave overnight in a covered container.You should test the saltiness at this stage too. If the vegetable taste too salty, drain some of the water and add clean water. But remember, you will be washing out some of the flavour, so try to add little salt and taste as you go.
NOTE: As this is a Thai recipe, its assuming that the ambient temperature is about 28-30 degrees Celsius. In a cooler climate, you would need to leave longer than overnight, and would then have to put them in a breathable vessel to let the gases escape.
The next day, wash rice as for preparing for cooking. Rinse it briefly first to take off any dust and particles, then add water and soak for a few minutes, stirring to release the starches. Once you have a fairly opaque looking water, drain and keep it. (Then add more clean water to your rice and cook and eat it, don’t discard it!)
Add this rice water to your vegetables (at this stage you could add whole chillis also) and according to the balmy temperatures in Thailand, expect to wait for 3-6 hours until it is soured enough to your liking. After that, put it in a jar (or even a plastic bag, Thai style!) and refrigerate. Of course if you are unlucky enough not to live in a tropical paradise, it could take a few days to a few weeks to sour enough. It will keep as per normal ferments – more sour the longer you keep it.