Place the pork belly in a thick bottomed non-reactive pan. Pour in the rum. Bring to the boil and cook until the liquid is reduced by half.
Pour in the Worcestershire Sauce, about two tablespoons of soy sauce and black vinegar. Lower the heat, cover and simmer for an hour and a half or until the pork is tender.
Add water or broth if there appears to be too little liquid at any stage. No more than a quarter cup at a time though to prevent the sauce from getting soupy.
Lift the drunken pork out of the sauce and transfer to a cutting board. Rest for 1o to 15 minutes before cutting.
While waiting for the drunken pork to cool, heat the remaining sauce to reduce to a couple of tablespoonfuls. Adjust the seasonings, if needed.
Meanwhile, make the mango salsa.