Hot Beef Sandwich Recipe

In a small bowl whisk together mayonnaise, prepared horseradish, Dijon mustard, lemon juice, salt and pepper until smooth. Taste and adjust horseradish for desired heat. Refrigerate until assembly.

Prepare vegetables

Heat 1 tablespoon olive oil and 1 tablespoon butter in a large skillet over medium-high heat until shimmering. Add sliced onions and a pinch of salt. Sauté, stirring occasionally, 6–8 minutes until onions are soft and beginning to brown.

Add sliced mushrooms to the skillet, increase heat slightly if needed, and cook another 5–6 minutes until mushrooms release moisture and brown. Season with 1 tsp salt and 1/2 tsp black pepper, stir to combine.

Add the shaved beef to the pan and toss just until warmed through, about 1–2 minutes (do not overcook thinly sliced roast beef). Remove pan from heat and keep warm. Reserve any pan juices to add to the gravy if desired.

In a separate small saucepan, melt 2 tablespoons beef drippings or butter over medium heat. Sprinkle in 2 tablespoons flour and whisk continuously to form a smooth roux, cooking 1–2 minutes until slightly golden.

Slowly whisk in 2 cups beef stock, then add 1 teaspoon Worcestershire sauce. Bring to a simmer, whisking to break up any lumps. Reduce heat to low and simmer 4–6 minutes until thickened to a gravy consistency. Season with 1/2 tsp salt and 1/4 tsp black pepper. If you reserved pan juices from the beef, whisk them in now for extra flavor.

Keep gravy warm over lowest heat, stirring occasionally. If too thick, thin with up to 1/4 cup additional stock or water.

Preheat oven broiler or set oven to 425°F (220°C) with rack in upper third. Brush both sides of each bread slice with melted butter (use the 2 tbs butter from Sandwich Base). Place on a baking sheet and toast under broiler or in oven until golden and crisp, about 2–4 minutes per side — watch closely to avoid burning.

In a nonstick skillet, heat 2 tablespoons vegetable oil over medium-high heat until shimmering. Crack eggs into the pan (work in batches if needed). Fry until whites are set but yolks are still runny, about 2–3 minutes for sunny-side up. Season each egg with a pinch of salt and pepper. For over-easy eggs, flip gently and cook 20–30 seconds more.

Place one toasted bread slice on each plate. Spread about 1 tablespoon horseradish mayo over each toast.

Divide the warm shaved beef, mushrooms and onions evenly among the four toasts, piling slightly high.

Ladle warm gravy over the beef on each open-faced sandwich, about 1/4 to 1/3 cup per sandwich, allowing some to run onto the plate.

Top each sandwich with a fried egg. Sprinkle chopped parsley over the eggs if using. Serve immediately while hot, with extra gravy on the side if desired.