Combine all marinade ingredients in a non-reactive bowl. Whisk together until well mixed. Put pork roast and marinade in a large Ziploc bag. Squeeze out all air. Let marinade for 2-4 hours (or overnight)
Preheat oven to 350 F.
Place pork roast on a roasting pan while reserving the marinade for a sauce. Roast pork for 2 hours, until the internal temperature is at least 160 F.
Meanwhile, pour the remaining marinade in a 4 cup measuring cup. Take your chicken broth and fill measuring cup to the 4 cup mark. Pour into medium saucepan and bring to a boil. Reduce heat and keep liquid at a gentle simmer. Reduce liquid to 2 cups. Add 2 TBS of good quality rice vinegar to finish the sauce.
After letting roast rest for 15-20 minutes, carve and pour sauce over it. Goes good with rice or fried potatoes.