Ingredients

  • 1 12 lbs lean ground beef
  • 2 tablespoons water
  • 2 teaspoons water
  • salt and pepper
  • 12 teaspoon baking soda
  • 2 12 lbs russet potatoes, peeled and cut into 1-inch chunks
  • 4 tablespoons unsalted butter, melted
  • 12 cup milk
  • 1 large egg yolk
  • 8 scallions, green parts only, sliced thin
  • 2 teaspoons vegetable oil
  • 1 onion, chopped
  • 4 ounces white mushrooms, trimmed and chopped
  • 1 tablespoon tomato paste
  • 2 garlic cloves, minced
  • 2 tablespoons madeira wine or 2 tablespoons ruby port
  • 2 tablespoons all-purpose flour
  • 1 14 cups beef broth
  • 2 teaspoons Worcestershire sauce
  • 2 sprigs fresh thyme
  • 1 bay leaf
  • 2 carrots, peeled and chopped
  • 2 teaspoons cornstarch

Method

  • 1.
  • Toss beef with 2 tablespoons water, 1 teaspoon salt, 1/4 teaspoon pepper, and baking soda in bowl until thoroughly combined.
  • Set aside for 20 minutes.
  • 2.
  • Meanwhile, place potatoes in medium saucepan; add water to just cover and 1 tablespoon salt.
  • Bring to boil over high heat.
  • Reduce heat to medium-low and simmer until potatoes are soft and tip of paring knife inserted into potato meets no resistance, 8 to 10 minutes.
  • Drain potatoes and return to saucepan.
  • Return saucepan to low heat and cook, shaking pot occasionally, until any surface moisture on potatoes has evaporated, about 1 minute.
  • Remove pan from heat and mash potatoes well.
  • Stir in melted butter.
  • Whisk together milk and egg yolk in small bowl, then stir into potatoes.
  • Stir in scallion greens and season with salt and pepper to taste.
  • Cover and set aside.
  • 3.
  • Heat oil in broiler-safe 10-inch skillet over medium heat until shimmering.
  • Add onion, mushrooms, 1/2 teaspoon salt, and 1/4 teaspoon pepper; cook, stirring occasionally, until vegetables are just starting to soften and dark bits form on bottom of skillet, 4 to 6 minutes.
  • Stir in tomato paste and garlic; cook until bottom of skillet is dark brown, about 2 minutes.
  • Add Madeira and cook, scraping up any browned bits, until evaporated, about 1 minute.
  • Stir in flour and cook for 1 minute.
  • Add broth, Worcestershire, thyme, bay leaf, and carrots; bring to boil, scraping up any browned bits.
  • Reduce heat to medium-low, add beef in 2-inch chunks to broth, and bring to gentle simmer.
  • Cover and cook until beef is cooked through, 10 to 12 minutes, stirring and breaking up meat chunks with 2 forks halfway through.
  • Stir cornstarch and remaining 2 teaspoons water together in bowl.
  • Stir cornstarch mixture into filling and continue to simmer for 30 seconds.
  • Remove thyme and bay leaf.
  • Season with salt and pepper to taste.
  • 4.
  • Adjust oven rack 5 inches from broiler element and heat broiler.
  • Place mashed potatoes in large zipper-lock bag and snip off 1 corner to create 1-inch opening.
  • Pipe potatoes in even layer over filling, making sure to cover entire surface.
  • Smooth potatoes with back of spoon, then use tines of fork to make ridges over surface.
  • Place skillet on rimmed baking sheet and broil until potatoes are golden brown and crusty and filling is bubbly, 10 to 15 minutes.
  • Let cool for 10 minutes before serving.