Cut beef steak lengthwise in half, then crosswise into 1/8-inch thick strips. Heat 12-inch nonstick skillet over medium-high heat until hot. Add half of beef; stir-fry 1-1/2 to 2 minutes or until outside surface of beef is no longer pink. Remove from skillet; keep warm. Repeat with remaining beef. Set aside.

In same skillet used to prepare beef, melt 2 teaspoons butter on medium high heat. Add 3 cups diced sweet onions. Cover and cook 5 to 7 minutes until onions are opaque and soft. Uncover skillet; cook 6 to 8 minutes until onions are golden brown, stirring occasionally. Add 1/2 cup red wine; simmer 2 to 4 minutes until liquid is almost evaporated. Stir in 1 can (14 to 14-1/2 ounces) reduced-sodium beef broth, 1/4 teaspoon salt and 1/4 teaspoon pepper. Cook about 20 minutes.

Add beef to sauce; cook 2 to 3 minutes or until beef is heated through.

Cut slits lengthwise in potatoes; open and fluff potatoes with fork. Divide beef mixture among potatoes. Top with cheese.