Easy Beef Stroganoff

Name: Easy Beef Stroganoff
Prep time: 5 min
Cook time: 15 min
Total time: 20 min
Cuisine: American, Eastern European
Ingredients: 2 tablespoons butter; 1/2 cup diced onions; 8 ounces sliced mushrooms; 2 tablespoons all-purpose flour; 1 1/2 cups beef broth; 1 (10.75-ounce) can condensed cream of mushroom soup; 2 tablespoons sour cream; Kosher salt, to taste; Freshly ground black pepper, to taste; 2 cups shredded cooked leftover beef, such as roast beef, pot roast, beef brisket, or deli roast beef; Cooked egg noodles, for serving; Freshly chopped parsley , optional, for garnish