The milk will caramelize, and the lactic acid will help make the pork tender. The milk solids will also start to separate from the liquid. This may not look so pretty, but it’s those curds that add so much flavor to the sauce and the dish. However, you may also choose to blend the sauce in a blender or food processor to emulsify it and make it smoother. (Many Italian Grandmas might be mad at you for this, but you decide!). I did that so that the generous amount of leeks I used in the braise could be incorporated into the sauce. The sauce was just amazing, and you should make sure to serve this with something starchy and also some crusty bread so you don't waste a drop of it.