I’m really excited to share this Grilled Steak Crostini with Horseradish Sauce Recipe with you—it’s honestly a total crowd-pleaser that feels both elegant and approachable. Whether you’re throwing a casual get-together or want to impress at a dinner party, these bite-sized steaks on crunchy crostini with that zingy horseradish sauce hit all the right notes. Plus, it’s one of those recipes that manages to look fancy without being complicated, which I always appreciate in the kitchen.

This recipe brings together satisfying textures and bold flavors in a way that feels special but totally doable. The creamy horseradish sauce adds a little kick that perfectly complements the rich filet mignon, while the caramelized onions provide a sweet counterbalance. I’ve made these a handful of times for friends, and watching everyone’s faces light up is honestly the best part. If you love steak and want to share something fun and flavorful, you’ll really enjoy making—and eating—this Grilled Steak Crostini with Horseradish Sauce Recipe.

Ingredients You’ll Need

Each ingredient here plays a key role in creating a balance of flavors and textures that make this dish shine. When shopping, look for quality steak and fresh baguette to maximize flavor, and don’t skip the horseradish—it’s the star in the sauce!

Filet Mignon Steaks: Choose a nice thick cut for tenderness and perfect grilling.
Olive Oil: Use good quality extra virgin for brushing the steak and crostini.
Steak Seasoning: A blend that includes salt, pepper, and herbs to enhance the steak.
Sour Cream: Look for full-fat for a rich, creamy base in the horseradish sauce.
Prepared Horseradish: This adds the horseradish bite—don’t use horseradish cream; straight prepared works best.
Dijon Mustard: Brings a touch of acidity and sharpness to the sauce.
Champagne Vinegar: I love this vinegar for its bright, slightly fruity tang; white wine vinegar works too.
Worcestershire Sauce: Adds a savory depth that rounds out the sauce.
Fresh Chives: Chop finely for a mild onion flavor and fresh color.
Day Old Baguette: Day-old bread is perfect for crostini because it crisps up beautifully without getting soggy.
Butter: Melted, for brushing on crostini to get that golden finish.
Garlic Clove: Optional, but rubbing the toasted crostini with garlic adds that extra kick of aroma.
Onion: For caramelizing, choose yellow or sweet onions—they become wonderfully sweet and luscious.
Sugar: Just a pinch to help the onions caramelize perfectly.
Kosher Salt: Essential for seasoning the onions and balancing flavors.
Balsamic Glaze: Optional drizzle for a sweet and tangy accent.

Variations

I love making this recipe my own depending on who I’m serving and what I have on hand. Don’t be afraid to mix it up — it keeps the dish fresh and exciting!

Variation: Swap filet mignon for flank steak or ribeye if you want a more affordable or fattier cut. Just adjust grilling time accordingly.
Variation: For a dairy-free horseradish sauce, try mixing prepared horseradish with vegan sour cream or Greek yogurt instead of traditional sour cream.
Variation: Add a layer of blue cheese or goat cheese on the crostini before topping with steak for a richer bite.
Variation: In warmer months, I sometimes add fresh arugula leaves for a peppery crunch that pairs beautifully with the horseradish sauce.
Variation: For a smoky flavor, try finishing the steak crostini on a charcoal grill or adding a dash of smoked paprika to the horseradish sauce.

How to Make Grilled Steak Crostini with Horseradish Sauce Recipe

Step 1: Season and Prep the Steak

I like to take my steaks out of the fridge about 30 minutes before grilling to come to room temperature—this helps them cook more evenly. Rub the filet mignon with olive oil and then generously season both sides with your steak seasoning. Don’t skimp on seasoning; it’s key for flavor!

Step 2: Make the Horseradish Sauce

Whisk together sour cream, prepared horseradish, Dijon mustard, champagne vinegar, Worcestershire sauce, and chopped chives in a bowl. Taste and adjust salt, pepper, or horseradish based on your spice preference. This sauce can be made a day ahead—it actually tastes better once the flavors meld together overnight.

Step 3: Caramelize the Onions

Heat olive oil and butter in a skillet over medium-low heat. Add diced onions, sprinkle with sugar, and season lightly with kosher salt. Cook slowly, stirring occasionally, until the onions are soft and golden brown, about 20 to 25 minutes. Patience here pays off—caramelized onions add a toasty sweetness you’ll love on these crostini.

Step 4: Prepare the Crostini

Preheat your oven or grill to about 375°F (190°C). Arrange your baguette slices on a baking sheet, brush each slice lightly with a mix of melted butter and olive oil. Toast until golden and crisp, about 8-10 minutes. If you want an extra garlic kick, rub the toasted crostini with a smashed garlic clove right after they come out of the oven.

Step 5: Grill the Steak

Grill your steaks on high heat for about 3-4 minutes per side for medium-rare, depending on thickness. Use tongs to flip—don’t poke it to keep those juices in. Let steak rest for 5 minutes after grilling to keep it tender and juicy, then slice thinly against the grain.

Step 6: Assemble Your Crostini

Spread a generous spoonful of horseradish sauce onto each crostini, top with a few slices of grilled steak, and then a bit of caramelized onion. If you’re feeling fancy, a drizzle of balsamic glaze and some fresh chopped chives on top make a beautiful finishing touch.

How to Serve Grilled Steak Crostini with Horseradish Sauce Recipe

Grilled Steak Crostini with Horseradish Sauce Recipe - Recipe Image

Garnishes

I usually go with fresh chopped chives or finely sliced scallion tops because they add a fresh oniony pop that’s not overpowering. Sometimes I also sprinkle a tiny pinch of flaky sea salt right before serving—it makes every bite a little more special.

Side Dishes

These crostini pair wonderfully with a crisp green salad dressed simply with lemon and olive oil. I’ve also served them alongside roasted veggies or even creamy mashed potatoes for a heartier meal. If you’re entertaining, a bowl of mixed olives and marinated artichokes adds a lovely Mediterranean vibe.

Creative Ways to Present

For parties, I like to arrange the crostini on a wooden board with small bowls of extra horseradish sauce and balsamic glaze nearby for dipping and drizzling. You can even layer the steak crostini with microgreens or edible flowers for a stunning appetizer that sparks conversation.

Make Ahead and Storage

Storing Leftovers

If you have leftovers, keep the steak slices and sauce stored separately in airtight containers in the fridge. The crostini are best eaten fresh but can be stored at room temperature for a few hours. This way, nothing gets soggy, and everything tastes fresh when you’re ready to enjoy the next day.

Freezing

I haven’t personally frozen the assembled crostini—they don’t hold up well after thawing—but you can freeze leftover grilled steak slices if wrapped tightly. When ready, thaw overnight in the fridge and reheat gently on the stovetop or in the oven.

Reheating

To reheat the steak, warm slices in a hot skillet for just a couple of minutes, flipping gently to avoid overcooking. Warm the horseradish sauce separately as it’s best served chilled or at room temperature. Toast fresh crostini to bring back that perfect crunch.

FAQs

Can I use a different cut of steak for this Grilled Steak Crostini with Horseradish Sauce Recipe?

Absolutely! While filet mignon is tender and perfect for quick grilling, you can substitute ribeye, sirloin, or flank steak too. Just be sure to adjust grilling times and slice thinly against the grain for the best texture.
How spicy is the horseradish sauce?

The heat of horseradish sauce depends on how much prepared horseradish you add. Start with less, then taste and add more if you want a bigger kick. It’s got a sharp, sinus-clearing bite but balances nicely with the creamy sour cream.
Can I make the caramelized onions ahead of time?

Yes! You can caramelize the onions a day ahead and store them in an airtight container in the fridge. Just warm them up gently before assembling your crostini for that perfect sweet-savory touch.
What’s the best bread for crostini?

A day-old baguette is ideal because it toasts crisply without becoming soggy. If you don’t have baguette, a rustic Italian loaf or ciabatta sliced thin also works well.
How do I keep crostini from getting soggy?

The key is to toast the bread thoroughly and keep it separate from moist ingredients until right before serving. Brushing with olive oil and butter helps create a moisture barrier, keeping them crisp longer.

Final Thoughts

This Grilled Steak Crostini with Horseradish Sauce Recipe has become one of my go-to appetizers because it’s simple yet packs incredible flavor and elegance. There’s something special about serving up these little bites that bring people together around the table. I hope you try this recipe soon—and when you do, be sure to savor every bite and enjoy the smiles it brings!