Instant Pot Beef Stroganoff

Name: Instant Pot Beef Stroganoff
Ingredients: 1 medium yellow onion; 12 ounces cremini mushrooms; 2 cloves garlic; 1 pound boneless sirloin steaks; 1 1/2 teaspoons kosher salt, plus more as needed; 1/2 teaspoon freshly ground black pepper, plus more as needed; 2 tablespoons vegetable oil; 2 tablespoons all-purpose flour; 1/4 cup dry white wine or dry sherry; 3 1/3 cups beef broth; 1 tablespoon Worcestershire sauce; 2 teaspoons Dijon mustard; 12 ounces dried wide egg noodles; 3/4 cup full-fat sour cream; Chopped fresh parsley leaves, for garnish (optional)