with Balsamic Vinegar Cranberry Sauce
Season with salt and pepper then sear tenderloin over medium-high heat in ½ T butter. Place in 450 degree oven and cook until @ 155 degrees, about 10 minutes.
Meanwhile, melt 1 T butter, then add onion and rosemary. Saute until onion softens. Add broth, cranberry sauce and vinegar and whisk until sauce melts. When pork is done, remove from pan and scrape any meat bits and juices into sauce. Boil about 6 minutes, season with salt and pepper.