Steak Crostini might just be my favorite appetizer to make! Perfectly toasted crostini gets topped off with creamy horseradish sauce, tender grilled steak, caramelized onions and a drizzle of balsamic glaze. It really doesn’t get much better than this!

Two pieces of steak crostini are placed on a white plate.

Steak Crostini

If you’re having guests over and you really feel like showing off, you’ve stumbled upon just the right recipe! Steak crostini is one of those finger foods that I love making when I really feel like pulling out all the stops. They’re flavorful, impressive, and actually hit the spot so you’re not starving before dinner!

There are three key elements to the very best steak crostini. First off is of course the crostini itself, which I’ve included steps for below. Then, each piece of crostini is topped generously with a creamy horseradish sauce that’s deliciously bold. And of course there’s tender, juicy steak topping it all off with a pile of caramelized onions.

I also like to drizzle on some balsamic reduction and fresh chives just to really send this appetizer over the top. After all, if it’s worth doing, it’s worth doing right! This easy steak crostini recipe is perfect for serving at cocktail parties, potlucks, and all other occasions.

Two seasoned pieces of steak are placed on a white plate.

Ingredient Notes

For the steak

  • Steaks – I like to use filet mignon for this recipe!
  • Olive Oil – You can swap this with avocado oil if you’d like.
  • Steak Seasoning

For the horseradish sauce

  • Sour Cream – I like to use regular sour cream with the full fat content (not low fat) for the creamiest results.
  • Horseradish – Be careful not to add too much. A little goes a long way!
  • Dijon Mustard – Don’t swap this with plain yellow mustard.
  • Champagne Vinegar – In a pinch, you can swap this for white wine vinegar but the flavor will be a little different.
  • Worcestershire Sauce – This adds the very best savory umami flavor.
  • Chives – Fresh chives add the best kick of freshness.
  • Salt and Pepper – Just enough to taste! For the best flavor, consider using kosher salt and freshly cracked black pepper.

For the crostini

  • Baguette – It should be about a day old, that way it’s slightly stale and sturdy.
  • Butter – You can use salted or unsalted, whichever you prefer.
  • Olive Oil – Avocado oil also works just fine.
  • Garlic – A smashed garlic clove is optional, but it adds a ton of flavor!

For the caramelized onions

  • Onion – A white or yellow onion are both great.
  • Olive Oil
  • Butter
  • Sugar – Just a sprinkle of sugar helps quicken the caramelizing process.
  • Salt
Two cooked steaks are placed next to a sheet pan filled with crostini.

How to Make Steak Crostini

Take a quick look at just how easy this recipe is! For a full list of step by step instructions, keep on scrolling down to the recipe card.

  1. Grill the steaks. Preheat the grill. While it’s heating up, season the steaks with salt and pepper on both sides. Add the steaks to the hot grill, close the lid and cook for about 4-5 minutes (or until a tasty golden brown crust has formed). Flip and keep cooking until the steaks are cooked the way you like them.
  2. Let the steaks rest. This is so important! If you cut into a steak too soon, you’ll dry it out. Transfer the cooked steaks to a platter, tent them with foil and let them rest for about 10 minutes.
  3. Make the horseradish sauce. Whisk together the sour cream, horseradish, dijon, vinegar, worcestershire sauce, salt, pepper and chives until combined.
  4. Make the crostini. Slice the baguette into 1/4 inch slices. Mix together the butter, oil and garlic, then brush the bread pieces with this mixture on each side. Place the bread on a baking sheet and bake at 375°F until lightly toasted. Flip and bake until toasted on the other side as well. Let the bread cool to room temperature prior to assembling the rest of the dish!
  5. Caramelize the onions. Heat oil and butter in a skillet. Add the onions and cook until caramelized. Stir every once in a while to avoid burning the onions. This should take you about 15-20 minutes or so. At the end of cook time, stir in a pinch of sugar. Season with a little salt.
  6. Assemble the crostini. Top each crostini with horseradish sauce, a slice of steak and caramelized onions. Garnish with some chives and balsamic glaze.
Several pieces of crostini are lined up.

Enjoy more of my favorite party appetizer recipes!

For more easy appetizer ideas, follow us on Instagram and Facebook!

Several pieces of crostini are lined up.

Get the Recipe: Grilled Steak Crostini with Horseradish Sauce

Steak crostini are an elegant and flavorful appetizer featuring thinly sliced, seared steak on toasted baguette slices. They are topped with sweet and savory caramelized onions and a creamy horseradish sauce for a perfect balance of textures and tastes. It's a simple yet impressive dish that's perfect for parties or gatherings.
No ratings yet


For the Steak

  • 8 ounces Filet Mignon Steaks
  • 2 tablespoons olive oil, if desired
  • 2 tablespoons Steak Seasoning

For the Horseradish Sauce

  • 1 cup sour cream
  • 1/4 cup prepared horseradish
  • 1 1/2 tablespoons dijon mustard
  • 1 teaspoon champagne vinegar
  • 1 teaspoon worcestershire sauce
  • 1/2 tablespoon fresh chopped chives
  • salt and pepper, to taste

For the Crostini

  • 1 Day old Baguette, cut into 1/4 inch slices
  • 2 tablespoons butter, melted
  • 1/4 cup olive oil
  • 1 garlic clove, smashed, optional

For the Caramelized Onions

  • 1 onion, diced
  • 1 tablespoon olive oil
  • 1/2 tablespoon butter
  • 1/4 teaspoon sugar
  • Kosher salt, to taste
  • Chopped Fresh Chives, optional
  • Balsamic Glaze, optional


  • 1 grill


To grill the steaks

  • Preheat gas grill to 450 degrees or prepare a charcoal grill.
  • Season the steaks liberally with kosher salt and black pepper on both sides.
  • Add the steaks to the grill and close the lid. Cook until a crust has formed and golden brown, approximately 4-5 minutes.
  • Flip the steaks and close the lid. Continue grilling for an additional 4-5 minute or until the desired degree of doneness. (see chart above for grilling times.) 125 degrees for medium rare.
  • Transfer the steaks to a platter and cover with foil.
  • Allow the steaks to rest for 10 minutes before serving. While the steak is resting, make the other items.

To Make the Horseradish Sauce

  • Whisk together the sour cream, horseradish, dijon, vinegar, worcestershire sauce, salt, pepper and chives.
  • Make the Crostini
  • Preheat oven to 375 degrees F (190 degrees C).
  • Slice the baguette crosswise into 1/4 inch thick slices
In a small bowl, stir together the butter, olive oil, and garlic. 
Brush the oil mixture on both sides of the bread. Arrange the bread on a baking sheet.
 Bake at 375 degrees F (190 degrees C) for 5 minutes, or until lightly toasted. Flip and bake for an additional 3-4 minutes until toasted and crisp.
Remove from the oven and cool to room temperature.

Make the Caramelized Onions

  • Heat the olive oil and butter in a skillet over medium high heat.
  • Add the onions and cook until deeply caramelized, stirring occasionally to avoid burning, approximately 15-20 minutes.
  • Stir in the sugar and cook for an additional 3-4 minutes.
  • Season with salt, to taste.
  • Top each Crostini with 1 teaspoon horseradish sauce.
  • Slice the steak across the grain and top each crostini with a slice of steak.
  • Top the steak with 1/2 tablespoon onions. Garnish with chopped chives and drizzle with balsamic glaze, if desired.


Each step can be made in advance to save time. Assemble the crostini right before serving to avoid soggy crostini.
Calories: 123kcal, Carbohydrates: 7g, Protein: 3g, Fat: 9g, Saturated Fat: 3g, Polyunsaturated Fat: 1g, Monounsaturated Fat: 5g, Trans Fat: 0.05g, Cholesterol: 15mg, Sodium: 106mg, Potassium: 73mg, Fiber: 0.5g, Sugar: 1g, Vitamin A: 109IU, Vitamin C: 1mg, Calcium: 29mg, Iron: 1mg