Whisk together all marinade ingredients in a medium bowl. Place pork in a large ziploc bag and add marinade. Seal bag and turn it several times to coat. Marinade overnight.
Preheat oven to 325F. Remove pork form bag and place on rack in a shallow roasting pan. Put marinade back in fridge for later. Roast pork, uncovered, for about 25-30 minutes per pound, until meat thermometer reads 155F. While roast is cooking, pour reserved marinade into small saucepan. Bring to boil, then reduce to low heat and simmer for 1 minute. Brush roast generously with marinade during last 20 minutes of cooking. Take pork out of the oven and cover loosely with foil. Let rest for 10 minutes before slicing thinly.