Purée all of the sauce ingredients (everything except the bay leaf, the pork and the buns) in a blender until smooth. If you have extra time, marinate the pork in the sauce overnight or for several hours before cooking.
Put sauce, bay leaf, and pork into a large pot and add 1 quart of water. Bring mixture to a boil and simmer, covered, turning frequently, for 2 hours or until the meat pulls apart easily with a fork.
Remove from heat and cool pork in the sauce. When cool, remove the pork from the sauce and shred into small pieces. Set aside.
Reduce the sauce by two thirds. Add the pork back to the sauce. Salt to taste. Remove bay leaf before serving. Serve hot over open-face hamburger buns.