Italian Pot Roast

INGREDIENTS

• 1 (8-oz.) package sliced fresh mushrooms
• 1 large sweet onion, cut in half and sliced
• 1 (3- to 4-lb.) boneless chuck roast, trimmed
• 1 teaspoon pepper
• 2 tablespoons olive oil
• 1 (1-oz.) envelope dry onion soup mix
• 1 (14-oz.) can beef broth
• 1 (8-oz.) can tomato sauce
• 3 tablespoons tomato paste
• 1 teaspoon dried Italian seasoning
• 2 tablespoons cornstarch