Preheat oven to 350°. In a large frying pan, heat 1 tbsp. oil over medium-high heat. Season pork with salt and pepper; brown lightly all over, about 5 minutes.
Transfer pork to a foil-lined 9- by 13-in. baking pan. Add remaining 1 tbsp. oil to frying pan, reduce heat to medium, and add onion. Cook, stirring, until softened, 3 minutes. Add garlic; cook 1 minute, then pour in chicken broth, cranberry sauce, rosemary, and vinegar. Cook 2 minutes.
Pour hot cranberry sauce over pork and bake, uncovered, until an instant-read thermometer inserted into meat registers 160°, about 20 minutes. Let pork rest 10 minutes, then slice and serve with sauce.
This recipe is awesome! The sauce keeps the pork moist, and the broth/rosemary/garlic prevent it from being too fruity with the cranberries (tho that would be ok with me!). Leftovers are great the next day. The sauce would be excellent with chicken, too.
This has become a favorite in my quick and easy recipe file. I have made it at least a dozen times since first seeing it in the Nov 2007 Sunset Magazine. It impresses guests and can be served with simple sides - I served it with roasted butternut squash and broccoli this time. Don't pass this one up!