1. Prepare the pork as directed and transfer it to a plate.
2. Set the now-empty skillet used to cook the port over medium-high heat and add the port and cherries. Cook, scrapping the pan bottom with a wooden spatula to loosen the browned bits, until the liquid reduces to about 2 tablespoons, 2 to 3 minutes. Increase the heat to hight and add the broth, rosemary, and any accumulated pork juices from the plate. Cook until the liquid reaches the consistency of maple syrup, about 2 minutes. Add salt and pepper to taste.
3. Reduce the heat to medium and return the pork to the pan, turning the meat to coat. Simmer to heat the pork through, about 3 minutes. Season with salt and pepper to taste. Transfer the pork to a serving plate and spoon the sauce over the meat. Serve immediately.