Prime Rib with Marsala-Mushroom Sauce

Ingredients

• 1 beef prime rib roast (5 lb.), 2 to 3 ribs
• 1/2 tsp. coarse black pepper, divided
• 1/4 tsp. kosher salt
• 2 Tbsp. butter
• 2 cups mixed sliced fresh mushrooms (baby bella, shiitake, oyster)
• 2 Tbsp. flour
• 2 Tbsp. GREY POUPON Dijon Mustard
• 1/4 tsp. dried thyme leaves
• 1/4 tsp. ground sage
• 1-1/2 cups fat-free reduced-sodium beef broth
• 1/4 cup Marsala wine