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Classic Steak Crostini with Creamy Horseradish Sauce and Caramelized Onions

Close-up of perfectly cooked steak crostini topped with creamy cheese, caramelized onions, and fresh chives.
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Create an elegant appetizer for your next gathering with this classic steak crostini recipe. It combines tender steak, sweet caramelized onions, and a zesty, creamy horseradish sauce on crisp toasted bread.

Ingredients

Scale
  • 1 pound flank steak or ribeye
  • 1 tablespoon olive oil, plus more for brushing
  • Salt and black pepper to taste
  • 1 French baguette, sliced into 1/2-inch thick pieces
  • 1 tablespoon butter
  • 2 large yellow onions, thinly sliced
  • 1/4 cup beef broth
  • 1/2 cup sour cream
  • 2 tablespoons prepared horseradish
  • 1 teaspoon Dijon mustard
  • 1 tablespoon fresh chives, chopped, for garnish

Instructions

  1. Prepare the caramelized onions: Melt the butter in a skillet over medium-low heat. Add the sliced onions and cook slowly, stirring occasionally, for 25 to 35 minutes until they are deep golden brown and soft. Add the beef broth during the last 5 minutes to help deglaze the pan. Remove from heat and set aside.
  2. Prepare the horseradish sauce: In a small bowl, whisk together the sour cream, prepared horseradish, and Dijon mustard. Season with a pinch of salt and pepper. Cover and refrigerate until ready to use.
  3. Cook the steak: Season the steak liberally with salt and pepper. Heat 1 tablespoon of olive oil in a cast-iron skillet over medium-high heat. Sear the steak for 3 to 4 minutes per side for medium-rare. Remove the steak from the pan and let it rest on a cutting board for 10 minutes before slicing thinly against the grain.
  4. Toast the crostini: Preheat your oven to 375°F (190°C). Brush both sides of the baguette slices lightly with olive oil. Arrange them on a baking sheet and bake for 6 to 8 minutes, flipping halfway through, until golden brown and crisp.
  5. Assemble the appetizers: Spread a small amount of the creamy horseradish sauce onto each toasted crostini slice. Top with a few thin slices of steak. Place a small spoonful of caramelized onions over the steak.
  6. Garnish the steak crostini with chopped fresh chives and serve immediately.

Notes

  • You can prepare the caramelized onions and horseradish sauce up to one day ahead to simplify assembly before your party.
  • For a richer flavor, use filet mignon or ribeye steak instead of flank steak.
  • If you prefer a tangier topping, substitute the sour cream in the sauce with plain Greek yogurt for a lighter texture.

Nutrition

Find it online: https://pureplatepath.com/steak-crostini-recipe-easy-entertaining/