"Salisbury Steak Upgrade: Knife & Fork Burgers with Onion-Mushroom Gravy & Garlicky Smashed Potatoes

Ingredients

• 1 ½ lb. baby white or yellow potatoes
• 4 cloves garlic, crushed
• Salt
• ¼ cup chopped fresh chives
• 3 tbsp. butter
• Pepper
• 4 tbsp. butter, cut into pieces
• 1 large or 2 medium onions, chopped
• ¼ lb. white mushroom caps, chopped or sliced
• 1 tbsp. fresh thyme or 1 tsp. dried thyme
• 1 tbsp. thinly sliced fresh sage or 1 tsp. dried sage
• 1 bay leaf
• 3 tbsp. flour
• 2 cups beef stock
• About 1 tbsp. soy sauce or shoyu (Japanese soy sauce)
• 1 ½ lb. ground sirloin
• Kosher salt and coarsely ground black pepper
• ½ cup dried breadcrumbs
• 1 large egg, beaten
• About 2 tbsp. Worcestershire sauce
• 2 tbsp. tomato paste, whisked with 3 tbsp. hot water
• 1 tbsp. (a scant palmful) dry mustard
• 1 tsp. (1/3 palmful) granulated garlic
• 1 tsp. (1/3 palmful) granulated onion
• 2 tbsp. olive oil
• Finely chopped parsley, for serving