Cut beef steak lengthwise in half, then crosswise into 1/8" thick strips. Heat 12" non-stick 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; remove from skillet. Add shiitake mushrooms; cook 4 to 6 minutes until mushrooms are lightly browned. Remove, keep warm with beef.

Bring balsamic vinegar to a boil in medium saucepan. Reduce heat; simmer 8 to 9 minutes until reduced to 2 tablespoons (consistency will be syrupy). Set aside to cool.

In same skillet used to prepare beef and mushrooms, heat olive oil over medium heat until hot. Add minced wild mushrooms; cook and stir 5 to 8 minutes until mushrooms are lightly browned. Add minced garlic; cook and stir 2 minutes. Add dry red wine; cook 2 to 5 minutes until liquid is completely evaporated. Dissolve cornstarch in 1 can (14 to 14.5 ounces) reduced-sodium beef broth. Add broth mixture and balsamic vinegar reduction to skillet; bring to a boil, stirring constantly. Reduce heat; simmer 15 to 20 minutes until mixture is reduced by half. Add in 1 tablespoon butter; stir until melted.

Add beef mixture to pan; cook 2 minutes until beef and mushrooms are heated through.

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