Steak Crostini with Horseradish Sauce & Caramelized Onions
This Steak Crostini with Horseradish Sauce & Caramelized Onions is a bold, elegant appetizer perfect for parties or holiday gatherings. Juicy, thin-sliced ribeye tops crisp toasted baguette with sweet, jammy onions and a creamy, zesty horseradish sauce creating the perfect bite of rich flavor, texture, and festive flair.
Equipment
- Cast Iron Skillet
- Sheet Tray
Ingredients
Steak
- 2 ribeye steaks (~2.75 lb total) ribeye steaks (bone‑in preferred) season with salt, rest then slice thin
Caramelized Onions
- 2 large yellow onions sliced, slow‑caramelized with rosemary
Horseradish Sauce
- 2 tbsp prepared horseradish
- 1 tbsp mayonnaise
- 1 tbsp sour cream
Other Essentials
- baguette, sliced for crostini base; toast until golden
- olive oil for onions and bread
- fresh rosemary sprigs
- fresh chives (finely chopped) for garnish
- flaky salt for finishing crostini
Instructions
- Pre‑heat oven to 375 °F (190 °C). Pat ribeye steaks dry, salt generously on all sides, and let them sit at room temperature (or briefly uncovered in fridge until cooking) to bring to temp. :contentReference[oaicite:2]{index=2}
- Slice the yellow onions, toss with olive oil, salt and a sprig of rosemary in a baking dish or cast iron pan. Place in cold oven as it preheats, then cook for ~35‑45 minutes, stirring every 10 minutes, until the onions are deep brown, sticky and jammy. :contentReference[oaicite:3]{index=3}
- While onions caramelize, heat a cast iron skillet (or grill) over medium‑high heat. Lightly oil the steaks and sear both sides until a golden crust forms. Use a meat thermometer and transfer to the oven if needed to finish to desired doneness (e.g., ~130 °F / 54 °C for medium‑rare). :contentReference[oaicite:4]{index=4}
- Remove steaks from heat and let rest for at least 10 minutes tented with foil. Then slice very thinly across the grain. :contentReference[oaicite:5]{index=5}
- Meanwhile, slice the baguette thinly, place on a sheet tray, drizzle with olive oil and toast in oven for about 5‑10 minutes until lightly golden. :contentReference[oaicite:6]{index=6}
- In a bowl, combine prepared horseradish, mayonnaise and sour cream. Season with salt and pepper to taste, adjust the horseradish for more kick if desired. :contentReference[oaicite:7]{index=7}
- Assemble the crostini: On each slice of toasted baguette, spread a dollop of horseradish sauce, layer with thinly sliced steak, top with some caramelized onions, and finish with another drizzle of the sauce. Garnish with fresh chives and flaky salt. Serve warm or at room temperature. :contentReference[oaicite:8]{index=8}
Notes
- You can prep the onions and sauce a day ahead to save time.
- Use any preferred steak cut (hanger, flank, sirloin) if ribeye isn’t available. Leftovers work great too.