DO-AHEAD TIP: Marinate pork for 4 to 6 hours (see recipe).
In a small bowl, combine mustard, oil, vinegar, salt and turmeric; gradually stir in milk until smooth; cover and refrigerate.
In a large zipper-topped plastic bag, combine soy sauce, ketchup, sugar, molasses and garlic; add pork, seal bag and turn to coat; refrigerate for 4 to 6 hours, turning occasionally.
Preheat oven to 350 degrees. Place pork in a shallow roasting pan (discarding marinade and bag) and bake, uncovered, for 40 minutes or until a meat thermometer registers 160-170 degrees. Let pork stand for 5 minutes then thinly slice.
Sprinkle sliced pork with sesame seeds, if desired, and serve with the mustard sauce.