Do Share Recipe

I love creating appetizers that feel fancy but are surprisingly simple to make at home. This Steak Crostini with Creamy Horseradish Sauce and Caramelized Onions Recipe quickly became a favorite for me. The combination of juicy, tender steak, sweet caramelized onions, and the zing of horseradish is irresistible.

I often make it for cocktail parties, family gatherings, or even a cozy date night at home. It’s elegant, flavorful, and perfect for impressing guests without spending hours in the kitchen, and you can also enjoy similar sweet treats like this pecan pie cookies recipe when planning a complete appetizer spread.

Steak Crostini with Creamy Horseradish Sauce and Caramelized Onions Recipe

Ingredients

Here’s everything you need to make this delicious appetizer. I also included tips on why certain ingredients work best.

For the Steak:

Filet mignon or beef tenderloin – Choose high-quality meat for tenderness. Let it come to room temperature for even cooking.
Unsalted butter – Allows better control of seasoning and helps in caramelizing onions.
Garlic powder – Prevents burning compared to fresh garlic and adds subtle flavor.
Dried thyme – Pairs beautifully with beef and enhances aroma.
Salt and black pepper – Season generously to bring out the natural flavors.

For the Crostini:

Baguette – A narrow, round baguette works best for even, well-shaped crostini.
Olive oil – Use a good-quality oil; it adds flavor and ensures golden, crispy bread, much like the crisp texture you get in a classic homemade mozzarella sticks recipe served as a party starter.

For the Horseradish Sauce:

Mayonnaise – Thick and creamy base for a smooth sauce.
Prepared horseradish – Adjust amount based on your spice preference.
Dijon mustard – Adds tang and depth.
Lemon juice – Fresh lemon balances the richness of the sauce.

For the Caramelized Onions:

Shallots – Sweeter and milder than regular onions.
Balsamic vinegar – Adds sharpness and enhances the golden color.
Brown sugar – Sweetens and balances the tangy flavors.
Salt and black pepper – Season as needed for perfect flavor.

Note: Several servings

Variations

Dairy-free: Use vegan butter for caramelizing onions and plant-based mayonnaise for the horseradish sauce.
Low-spice: Reduce or omit horseradish if you prefer a milder sauce.
Alternative meats: Substitute steak with grilled chicken or portobello mushrooms for a different twist.
Add-ins: Top with blue cheese crumbles or fresh arugula for added flavor.

Cooking Time

Prep Time: 20 minutes
Cooking Time: 40 minutes
Total Time: 1 hour

Equipment You Need

Skillet – For searing steak to perfection.
Saucepan – Caramelize onions evenly.
Baking sheet – Toast crostini slices.
Knife – Slice steak and shallots thinly.
Mixing bowls – Combine horseradish sauce ingredients.

How to Make Steak Crostini with Creamy Horseradish Sauce and Caramelized Onions

Season the Steak

I start by sprinkling the steak with salt, black pepper, garlic powder, and thyme. Letting it rest for at least 30 minutes allows the flavors to penetrate deeply, ensuring a juicy bite.

Mix the Horseradish Sauce

In a bowl, I whisk together mayonnaise, horseradish, Dijon mustard, and fresh lemon juice. Season to taste and refrigerate until assembly—it’s simple but packs a punch of flavor.

Sauté the Shallots

I melt butter in a saucepan, add the shallots, and cook gently until soft. Then I stir in balsamic vinegar, brown sugar, salt, and pepper, letting them caramelize into a golden, sweet topping over 30 minutes.

Sear the Steak

I sear the steak in olive oil over medium-high heat to my preferred doneness. Resting it for 15 minutes afterward ensures the meat stays tender and juicy before slicing thinly.

Make the Crostini

I brush baguette slices with olive oil and bake them at 375°F for 5–7 minutes until golden. They’re crisp, perfect for holding all the toppings.

Assemble and Garnish

I spread the horseradish sauce on each crostini, add thin slices of steak, and top with caramelized shallots. A few fresh herbs like thyme or parsley make it look stunning and add freshness.

Additional Tips for Making this Recipe Better

I always rest the steak; it makes the meat melt-in-your-mouth tender.
Using day-old bread ensures extra crispy crostini.
Slicing steak thinly against the grain gives a more elegant bite.
Preparing onions and sauce a day ahead saves stress on the day of serving.
Watch the shallots closely—they can burn quickly!
Fresh herbs on top balance flavors and elevate presentation.

How to Serve Steak Crostini with Creamy Horseradish Sauce and Caramelized Onions

Serve warm or at room temperature for the best experience. Arrange crostini on a decorative platter, drizzle any extra sauce over the top, and garnish with thyme or parsley. Pairing with a crisp white wine or a light cocktail makes it a perfect appetizer for parties or intimate gatherings.

Nutritional Information

Here’s a quick look at the nutrition per serving:

Calories: Approximately 220
Protein: 12g
Carbohydrates: 15g
Fat: 14g

Make Ahead and Storage

Storage

I store each component separately in the refrigerator for up to 48 hours. Steak should remain whole and sliced just before serving.

Freezing

The steak and onions can be frozen individually for up to a month, but crostini is best toasted fresh.

Reheating

I pop crostini back in the oven for a few minutes to crisp before assembling, and gently reheat steak slices if needed.

Why You’ll Love This Recipe

This is more than just an appetizer; it’s a show-stopper.

Easy yet impressive: Looks fancy but is surprisingly simple to make.
Flavor-packed: Juicy steak, sweet onions, and zesty horseradish combine perfectly.
Versatile: Works for parties, holidays, or romantic dinners.
Customizable: Adjust horseradish, toppings, or bread for your taste.
Make-ahead friendly: You can prep most components ahead of time to save stress.

This Steak Crostini with Creamy Horseradish Sauce and Caramelized Onions is my go-to recipe when I want something impressive but easy. Tender steak, crispy crostini, and flavorful toppings come together in each bite, making it an appetizer everyone will rave about.

Ben Carraoli