Place the flour, salt, and pepper in a small bowl. Rub 1 tablespoon of the flour mixture onto the beef Heat the oil in a large nonstick skillet over medium high heat. Add the beef and cook, turning frequently, until browned, 6-8 minutes.

Place the vegetables for stew and the remaining flour mixture in a 5 or 6 quart slow cooker; mix well. Place the beef on top of the vegetables. Combine the soup, mustard, and thyme in a small bowl; pour over the beef Cover and cook until the beef and vegetables are fork tender, 5 6 hours on high or 10 12 hours on low.

Transfer the beef to a cutting board and keep warm. Remove the vegetables with a slotted spoon to a bowl; set aside. Pour the sauce into a medium saucepan; bring to a boil over medium high heat. Boil, stirring occasionally, until the sauce is slightly thickened and reduced to 1 1/2 cups, 6-8 minutes. Cut the beef into 16 slices; transfer to a serving platter. Spoon the vegetables around the beef and serve with the sauce.