In the Chinese diet, milk and cheese, the well-recognized sources of calcium and phosphorus, are not used. A typical Chinese dish, which is called ‘sweet-sour-spareribs,’ was analyzed as a possible source of these elements.

From this research:

“Sweet-sour-spareribs” was often consumed by a woman after she gave birth.

The vinegar extracted huge amounts of calcium from the bones, giving the mother a much-needed source of calcium as she nursed her child.

From Marks Daily Apple