Heat 1 tablespoon oil in a 12-inch skillet over medium-high heat. Add the beef and cook until well browned on both sides. Remove the beef from the skillet. Pour off any fat.
Heat the remaining oil in the skillet. Add the onion and pepper and cook for 1 minute, stirring occasionally. Add the garlic and cook until the vegetables are tender-crisp, stirring often.
Stir the soup, water, vinegar and rosemary in the skillet and heat to a boil. Return the beef to the skillet. Reduce the heat to medium. Stir in the spinach. Cover and cook the beef for 2 minutes for medium or until desired doneness. Serve the beef and vegetable mixture with the potatoes.