From https://www.westonaprice.org/health-topics/food-features/lacto-fermentation/?fbclid=IwAR0_SZV5yz-0y2hFfYGw-tfeyhJ3IdYcwKhUPs726wwVkpq_9pcnwJmETFU#gsc.tab=0  

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Lacto-fermented condiments are easy to make. Fruits and vegetables are first washed and cut up, mixed with salt and herbs or spices and then pounded briefly to release juices. They are then pressed into an airtight container. Salt inhibits putrefying bacteria for several days until enough lactic acid is produced to preserve the vegetables for many months. The amount of salt can be reduced or even eliminated if whey is added to the pickling solution. Rich in lactic acid and lactic-acid-producing bacteria, whey acts as an inoculant, reducing the time needed for sufficient lactic acid to be produced to ensure preservation. Use of whey will result in consistently successful pickling; it is essential for pickling fruits. During the first few days of fermentation, the vegetables are kept at room temperature; afterwards, they must be placed in a cool, dark place for long-term preservation. 

It is important to use the best quality organic vegetables, sea salt and filtered or pure water for lacto-fermentation. Lactobacilli need plenty of nutrients to do their work; and, if the vegetables are deficient, the process of fermentation will not proceed. Likewise, if your salt or water contains impurities, the quality of the final product will be jeopardized.

About one inch of space should be left between the top of your vegetables with their liquid and the top of the jar, as the vegetables and their juices expand slightly during fermentation. 

Be sure to close the jars very tightly. Lacto-fermentation is an anaerobic process and the presence of oxygen, once fermentation has begun, will ruin the final product.

Lacto-fermentation is an artisanal craft that does not lend itself to industrialization. Results are not always predictable. For this reason, when the pickling process became industrialized, many changes were made that rendered the final product more uniform and more saleable but not necessarily more nutritious. Chief among these was the use of vinegar for the brine, resulting in a product that is more acidic and not necessarily beneficial when eaten in large quantities; and of subjecting the final product to pasteurization, thereby effectively killing all the lactic-acid-producing bacteria and robbing consumers of their beneficial effect on the digestion.