Beef Mushroom Guinness Pie

Ingredients

• 2 pounds beef round (cut into 2-inch cubes)
• 1/2 cup all-purpose flour
• 1 teaspoon black pepper
• 1/2 teaspoon garlic powder
• 1/2 teaspoon onion powder
• 1/2 teaspoon salt
• 3-4 tablespoons olive oil (for browning the beef)
• 1 large yellow onion (thinly sliced)
• 2 cloves garlic (minced)
• 14 ounces button mushrooms (thinly sliced (Baby Bella mushrooms can be used))
• 5 large carrots (peeled and cut into 1-inch chunks)
• 2 stalks celery (cut into 1/4-inch pieces)
• 2 cups Guinness Stout
• 1 cup fat-free beef broth
• 2-3 dashes Worcestershire sauce
• 1/2 teaspoon dry ground mustard (I use Coleman's dry mustard)
• Salt and pepper (to taste)
• 1 teaspoon cornstarch
• 4 sprigs fresh parsley
• 2 sprigs fresh thyme
• 1 bay leaf
• 1 sprig fresh rosemary
• Kitchen twine
• 1 package Puff Pastry (17.3 ounces)
• 1 medium egg (whisked well)