If conditions permit, you can also cook sour plum juice yourself. The firing method is as follows:
Mume 100g (available in Chinese medicine shops), 600g of brown sugar, 25g of osmanthus fragrans (not available) and clear water 1500g. First, clean the ebony, put it in a pot filled with clear water and boil it, then add brown sugar and osmanthus, and then boil it. After cooling, filter with gauze.