Serve slices of this roast pork tenderloin on a bed of roasted potatoes, sauteed radicchio, and green beans--all tossed with balsamic vinegar--for a dish that's as colorful as it is flavorful.
Heat oven to 400 degrees F. Toss potatoes with 1 tablespoon of the oil and 1/2 teaspoon of the rosemary. Place in large roasting pan and roast at 400 degrees F for 5 minutes.
Sprinkle pork tenderloin with the pepper, remaining 1/2 teaspoon rosemary and 1/2 teaspoon of the salt.
After 5 minutes, nestle pork in center of potatoes, pushing them to either side. Roast 25 more minutes or until internal temperature of pork registers 155 degrees F on an instant-read thermometer.
Cut radicchio into 1/2-inch slices (4 cups total). When the pork has 10 minutes left to cook, heat the remaining 1 teaspoon oil in a large nonstick skillet over medium-high heat. Add green beans and onions and sprinkle with remaining salt; cook 3 minutes. Add radicchio and cook for 6 minutes, stirring occasionally, until radicchio begins to wilt and green beans are crisp-tender. Stir in garlic and balsamic vinegar; cook for 1 minute.
Remove pork and potatoes from oven; add potatoes to skillet and stir to combine. Slice pork into 1/2-inch slices. Transfer contents of skillet to a serving platter and top with pork slices. Serve immediately.