Open-Faced Steak Sandwich With Horseradish Cream and Arugula

Quick Recipe Version (TL;DR)

• Yield: 4 open-faced sandwiches (4 servings)
• Prep Time: 20 minutes
• Cook Time: 20 minutes
• Total Time: 40 minutes

Quick Ingredients

• 1 1/2 lb (680 g) sirloin steak, 1–1 1/2 inch thick
• 4 thick slices sourdough bread
• 2 cups loosely packed baby arugula
• 1 large yellow onion + 1/2 cup buttermilk (or milk)
• 1/2 cup all-purpose flour + 1/4 cup cornstarch
• Neutral oil for frying + 1–2 tbsp olive oil or soft butter
• 1/2 cup sour cream, 2 tbsp prepared horseradish, 1 tbsp mayo, 1 tsp Dijon, 1 tsp lemon juice
• Salt, black pepper, garlic powder, paprika, optional Worcestershire, flaky salt

Do This

• 1. Stir together sour cream, horseradish, mayo, Dijon, lemon, seasoning (and Worcestershire, if using). Chill.
• 2. Soak thin onion slices in buttermilk; toss with seasoned flour/cornstarch, then fry in hot oil (350°F / 175°C) until crisp and golden. Drain on paper towels.
• 3. Pat steak dry; rub with oil, salt, pepper, and garlic powder. Grill or pan-sear over medium-high heat 3–5 minutes per side to desired doneness. Rest 5–10 minutes.
• 4. While steak rests, brush sourdough with oil or butter and toast in a skillet, on the grill, or under the broiler until crisp and golden.
• 5. Slice steak thinly against the grain.
• 6. To assemble: spread toasted bread with horseradish cream, top with arugula, pile on sliced steak, add more sauce, then finish with a mound of crispy onions and flaky salt.

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Why You’ll Love This Recipe

• Big steakhouse flavor in a hand-held, open-faced sandwich that feels special but is weeknight-friendly.
• Sharp, creamy horseradish sauce cuts through the rich beef for a perfectly balanced bite.
• Crispy fried onions and peppery arugula add crunch, freshness, and color in every layer.
• Flexible cooking: grill or pan-sear the steak, depending on the weather and your equipment.

Grocery List

• Produce: 1 large yellow onion, 2 cups baby arugula, 1 lemon (for juice)
• Dairy: Sour cream, buttermilk (or whole milk), butter (if using for toast)
• Pantry: Sirloin steak, sourdough bread, prepared horseradish, mayonnaise, Dijon mustard, Worcestershire sauce, all-purpose flour, cornstarch, neutral frying oil, olive oil, kosher salt, black pepper, garlic powder, paprika, flaky sea salt (optional)

Full Ingredients

For the Steak

• 1 1/2 lb (680 g) sirloin steak, about 1–1 1/2 inch thick
• 1 tbsp olive oil
• 1 1/2 tsp kosher salt
• 1 tsp freshly ground black pepper
• 1 tsp garlic powder

For the Horseradish Cream

• 1/2 cup (120 g) sour cream
• 2 tbsp prepared horseradish, drained (use 3 tbsp for extra heat)
• 1 tbsp mayonnaise
• 1 tsp Dijon mustard
• 1 tsp freshly squeezed lemon juice
• 1/2 tsp Worcestershire sauce (optional, for depth)
• 1/4 tsp kosher salt, or to taste
• 1/8 tsp freshly ground black pepper

For the Crispy Fried Onions

• 1 large yellow onion, very thinly sliced into rings or half-moons (about 2 cups packed)
• 1/2 cup (120 ml) buttermilk (or whole milk)
• 1/2 cup (60 g) all-purpose flour
• 1/4 cup (30 g) cornstarch
• 1/2 tsp kosher salt
• 1/4 tsp paprika (sweet or smoked)
• Neutral oil for frying (about 1–1 1/2 cups, such as canola, vegetable, or peanut oil)

For Assembly

• 4 thick slices sourdough bread (about 3/4 inch / 2 cm thick)
• 1–2 tbsp olive oil or softened butter (for toasting the bread)
• 2 cups loosely packed baby arugula (about 2 oz / 60 g)
• Extra horseradish cream, for drizzling
• Flaky sea salt, for finishing (optional)
• Freshly ground black pepper, for serving (optional)

Step-by-Step Instructions

Step 1: Make the Horseradish Cream

In a small bowl, combine the sour cream, prepared horseradish, mayonnaise, Dijon mustard, lemon juice, Worcestershire sauce (if using), salt, and black pepper. Stir until completely smooth and well blended.

Taste and adjust the seasoning: add a bit more horseradish if you like a stronger kick, or a pinch more salt if it tastes flat. Cover and refrigerate while you prepare the rest of the recipe. Chilling helps the flavors meld and the sauce thicken slightly.

Step 2: Prep the Onions for Frying

Peel the onion and slice it as thinly as you can into rings or half-moons. Aim for about 1/8 inch (3 mm) thick so they crisp quickly.

Place the onion slices in a bowl and pour the buttermilk (or milk) over them. Toss to coat, making sure all the onions are submerged. Let them soak for at least 10 minutes while you mix the dry coating.

In a separate bowl, whisk together the flour, cornstarch, kosher salt, and paprika. This mixture will give you light, shatteringly crisp onions.

Step 3: Fry the Crispy Onions

Pour about 1–1 1/2 inches (2.5–4 cm) of neutral oil into a heavy skillet or saucepan. Heat over medium-high heat until the oil reaches 350°F (175°C). If you do not have a thermometer, drop in a tiny bit of the flour mixture; it should sizzle immediately but not burn.

Working in small batches, lift a handful of onions from the buttermilk, let the excess drip off, then toss them in the flour mixture, separating the strands so they are lightly and evenly coated. Shake off any excess flour.

Carefully add the coated onions to the hot oil. Fry for 2–3 minutes, stirring gently with tongs or a slotted spoon, until golden brown and crisp. Transfer the fried onions to a plate lined with paper towels to drain. Immediately sprinkle with a pinch of salt while they are still hot.

Repeat with the remaining onions, allowing the oil to return to 350°F (175°C) between batches. Set the crispy onions aside. They will stay crunchy for quite a while.

Shortcut option: If you are in a hurry, you can use good-quality store-bought crispy fried onions and skip Steps 2 and 3.

Step 4: Season and Cook the Steak (Grill or Pan)

Pat the sirloin steak very dry on all sides with paper towels. This helps you get a better sear. Rub the steak with the olive oil, then season evenly with the kosher salt, black pepper, and garlic powder, pressing the seasonings gently into the meat.

For grilling: Preheat your grill to medium-high heat (about 425–450°F / 220–230°C). Clean and oil the grates. Place the steak on the grill and cook for about 3–5 minutes per side, depending on thickness and desired doneness. For medium-rare, aim for an internal temperature of 130–135°F (54–57°C); for medium, 135–145°F (57–63°C).

For pan-searing: Heat a heavy skillet (cast iron is ideal) over medium-high heat until very hot. Add a thin film of oil, then lay the steak in the pan. Sear without moving for 3–5 minutes until a deep brown crust forms. Flip and cook another 3–5 minutes, or until it reaches your preferred doneness.

Transfer the cooked steak to a cutting board, tent loosely with foil, and let it rest for 5–10 minutes. Resting allows the juices to redistribute so the meat stays moist when sliced.

Step 5: Toast the Sourdough and Prep the Greens

While the steak rests, prepare the bread. Brush both sides of each sourdough slice with olive oil or spread one side lightly with softened butter.

To toast in a skillet: Heat a large skillet over medium heat. Place the bread in the pan (oiled/buttered side down if only one side is coated) and toast for 2–3 minutes per side, until golden brown and crisp at the edges.

To toast on the grill: Place the bread slices directly on the grill grates over medium heat and toast 1–2 minutes per side, watching carefully so they do not burn.

To toast under the broiler: Place bread on a baking sheet and broil on high for 1–3 minutes, flipping once, until golden and crisp. Keep a close eye on it; bread can go from perfect to burnt quickly.

Rinse and dry the arugula (if not pre-washed) and set aside.

Step 6: Slice the Steak and Assemble the Open-Faced Sandwiches

Once the steak has rested, use a sharp knife to slice it thinly against the grain. Cutting against the grain shortens the muscle fibers and makes each bite more tender. Aim for slices about 1/4 inch (6 mm) thick.

Lay the toasted sourdough slices on plates or a serving board. Spread each slice generously with horseradish cream, reserving some for drizzling on top.

Scatter a small handful of arugula over each piece of bread. Pile the sliced steak on top of the arugula, dividing it evenly among the four slices. Spoon or drizzle a bit more horseradish cream over the steak.

Finish each sandwich with a generous mound of crispy fried onions. If you like, sprinkle with a pinch of flaky sea salt and a grind of black pepper for extra flavor and texture.

Serve immediately while the steak is warm, the bread is crisp, and the onions are crunchy.

Pro Tips

• Dry steak = better crust. Really pat the steak dry before seasoning so it can sear instead of steam.
• Slice against the grain. Look for the direction of the muscle fibers in the sirloin and cut across them, not parallel, for the most tender slices.
• Do not overcrowd the onions. Fry in small batches so the oil temperature stays hot and the onions get crisp instead of soggy.
• Adjust the heat of the sauce. Start with 2 tbsp horseradish, then add more to taste. Different brands vary a lot in intensity.
• Warm plates if possible. Serving on slightly warm plates helps keep the steak and bread from cooling too quickly.

Variations

• Cheesy upgrade: Add a thin layer of sliced provolone or sharp white cheddar on the sourdough and melt it under the broiler before adding arugula and steak.
• Caramelized onion twist: Skip the fried onions and instead top the sandwich with deeply caramelized onions for a sweeter, softer contrast.
• Spice it up: Add a pinch of cayenne or a few dashes of hot sauce to the horseradish cream, and sprinkle the finished sandwich with crushed red pepper flakes.

Storage & Make-Ahead

The elements of this sandwich keep better separately than assembled.

Horseradish cream: Store in an airtight container in the refrigerator for up to 3 days. Stir before using. The flavor may mellow slightly over time; add a bit more horseradish if needed.

Steak: Cooked steak can be refrigerated, tightly wrapped, for up to 3 days. For best texture, bring to room temperature for 20–30 minutes or gently warm in a low oven (275°F / 135°C) until just heated through.

Crispy onions: Once completely cool, store in an airtight container at room temperature for up to 1 day. If they soften, re-crisp briefly on a baking sheet in a 350°F (175°C) oven for 5–8 minutes.

Bread and assembly: Toast the bread and assemble the sandwiches right before serving so the bread stays crisp and the onions stay crunchy. This recipe is best enjoyed fresh, but leftovers can be eaten cold or at room temperature; the textures will be softer but still tasty.

Nutrition (per serving)

Approximate values per open-faced sandwich (1/4 of recipe): about 700 calories; 38 g protein; 45 g fat; 36 g carbohydrates; 3 g fiber; 5–6 g sugar. Actual values will vary based on exact ingredients, portion sizes, and frying oil absorption.