Fermentation is a traditional process to keep some vegetables eatable for many month, sometimes years. The natural fermentation will produce some CO2 and lactic acids wich will protect the vegetables from other unwanted bacterias. This process is famous for cabbage (choucroute-sauerkraut), pickles (cornichons, concombres), green beans (Local tradition, Alsace, France) but results are great with carots, celeriac, keleks and many other vegetables.
Preparation is simple but requires a lot of attention and hygiene, to avoid the development of undesirable and pathogens bacterias. As the vegetables are not boiled, nutrients are preserved and even enhanced by the fermentation. Soy sauce, tempeh and miso are produced with soy fermentation.