Put all the ingredients in a larger jar - I used a 5 liter water bottle - eventually cut it in the mouth, to make it wider.
Add water and dissolved yeast, mix everything well. Cover the bottle / jar with a gauze or towel and leave for 1-2 days until it penetrates and acidifies. Periodically taste it - strain it and put it in the fridge when it seems salty enough. In a warm place it is done even in one day.
Be very careful not to put a tight lid on the bottle - it will definitely explode and do your job not very pleasant.