Super Flavorful Salisbury Steak

Ingredients

For the Steaks:

• 1 lb ground beef (453g)
• ⅓ cup plain panko breadcrumbs (20g)
• 1 large egg
• 2 Tablespoons tomato paste
• 2 Tablespoons coarse stone ground mustard
• 2 Tablespoons worcestershire sauce
• 1 Tablespoon light brown sugar, firmly packed
• 1 teaspoon apple cider vinegar
• 1 teaspoon onion powder
• 1 teaspoon garlic powder
• 1 teaspoon salt
• ½ teaspoon ground black pepper

For Cooking:

• 1 Tablespoon olive oil

Gravy:

• 2 Tablespoons unsalted butter
• 1 cup finely chopped yellow onion (140g/1 medium yellow onion)
• 1 ½ cups sliced mushrooms (optional, I use baby bella, 226g)
• 2 Tablespoons all-purpose flour
• 2 Tablespoons worcestershire sauce
• 1 Tablespoon tomato paste
• ½ teaspoon salt
• ½ teaspoon ground black pepper
• ¼ teaspoon onion powder
• ¼ teaspoon garlic powder
• 2 cups beef broth (see note) (473ml)