My Family's Favorite Classic Salisbury Steak

Ingredients

• 1 lb ground beef (80% lean)
• 1/2 cup breadcrumbs
• 1/4 cup milk
• 1 large egg, beaten
• 1 small onion, finely chopped
• 1 tsp garlic powder
• 1/2 tsp salt
• 1/2 tsp black pepper
• 1 tsp Worcestershire sauce
• 2 tbsp unsalted butter
• 1 tbsp olive oil
• 8 oz mushrooms, sliced
• 1 cup beef broth
• 2 tbsp all-purpose flour
• 1 tsp soy sauce
• 1/2 tsp dried thyme
• Salt and pepper to taste