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This elegant steak crostini with horseradish creates the perfect bite sized appetizer for your next gathering. The combination of tender filet mignon, sweet caramelized onions and zesty horseradish sauce on crispy baguette slices delivers an explosion of flavors that will impress even the most discerning guests.
I first made these crostini for a holiday cocktail party last year and they disappeared faster than any other appetizer. Now they've become my signature dish whenever we host friends who appreciate good food with their drinks.
Ingredients
- Filet mignon The tender cut ensures melt in your mouth bites even when thinly sliced
- Steak seasoning A quality blend adds depth without overpowering the meat
- Sour cream Creates the creamy base for the horseradish sauce
- Prepared horseradish Provides the signature zesty kick that cuts through the richness
- Dijon mustard Adds tanginess and complexity to the sauce
- Champagne vinegar Brings brightness and acidity to balance flavors
- Worcestershire sauce Delivers umami depth to enhance the beef flavor
- Fresh chives Their mild onion flavor and bright color make the perfect garnish
- Day old baguette Slightly dried bread makes for better crostini that won't get soggy
- Butter Combined with olive oil for perfect toasting and flavor
- Olive oil Use a good quality oil as it impacts the final taste
- Garlic clove Rubbed on warm toast for subtle aromatic flavor
- Onion The caramelization process transforms it into sweet tender bits
- Sugar Helps accelerate the caramelization process for the onions
- Balsamic glaze The finishing drizzle adds sweet acidity and visual appeal
Step-by-Step Instructions
- Prepare the Steak
- Heat your grill to a hot 450°F. Season the filet mignon generously with steak seasoning on all sides. Grill for 4 to 5 minutes per side until the internal temperature reaches 125°F for medium rare. This temperature ensures the steak will remain tender and juicy. Remove from heat and let rest for at least 10 minutes before slicing thinly. The resting period is crucial as it allows the juices to redistribute throughout the meat.
- Make the Horseradish Sauce
- In a medium bowl whisk together the sour cream, prepared horseradish, dijon mustard, champagne vinegar, worcestershire sauce, and chopped chives. Season with salt and freshly ground black pepper to taste. The sauce should have a zesty kick but still be creamy and smooth. This can be made up to two days ahead and stored in an airtight container in the refrigerator.
- Toast the Crostini
- Slice the day old baguette into half inch rounds. In a small bowl combine melted butter, olive oil and minced garlic. Brush this mixture onto both sides of each bread slice. Arrange in a single layer on a baking sheet and bake at 375°F for about 5 minutes per side until crisp and golden brown. The edges should be crispy while the centers remain slightly chewy for the perfect texture contrast.
- Caramelize the Onions
- Heat a tablespoon each of olive oil and butter in a large skillet over medium low heat. Add the diced onion and cook slowly stirring occasionally for 15 to 20 minutes until deeply golden and sweet. Add the sugar and continue cooking for another 3 to 4 minutes until the onions are richly caramelized. This slow cooking process transforms the sharp onion flavor into sweet jammy perfection.
- Assemble the Crostini
- Spread a generous layer of horseradish sauce on each toasted baguette slice. Top with a thin slice of the rested filet mignon followed by a spoonful of caramelized onions. Garnish with additional fresh chives and a light drizzle of balsamic glaze just before serving. The assembly should happen right before serving to maintain the crisp texture of the bread.
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The horseradish sauce is truly the heart of this recipe. My grandmother always added a splash of vinegar to her horseradish preparations claiming it preserved the heat while balancing the flavors. I've continued this tradition and find it makes all the difference in the final taste profile.
Make Ahead Magic
The beauty of this appetizer lies in its make ahead potential. The horseradish sauce actually improves after sitting in the refrigerator for a day as the flavors meld together. The onions can be caramelized up to three days ahead and stored in an airtight container. Even the crostini can be toasted a day in advance and kept in a sealed container at room temperature. The steak is best cooked the same day but can be grilled a few hours ahead and served at room temperature. This preparation flexibility makes it perfect for entertaining when you want to enjoy your guests rather than being stuck in the kitchen.
Perfect Pairings
These sophisticated steak crostini pair beautifully with bold red wines like Cabernet Sauvignon or Malbec which complement the rich beef and stand up to the zesty horseradish. For a complete appetizer spread consider serving alongside something lighter like a citrus salad or vegetable crudités with herb dip. If serving as part of a larger menu they transition perfectly from cocktail hour into dinner making them versatile for multiple course events.
Temperature Matters
The temperature of each component significantly impacts the overall experience of this dish. The horseradish sauce should be chilled but not ice cold which would mute its flavors. The caramelized onions are best served warm or at room temperature which highlights their sweetness. The crostini should be completely cooled after toasting to maintain crispness. Most importantly the steak should be served at room temperature rather than chilled which allows its full flavor to shine through and prevents the fat from becoming waxy on the palate.
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Recipe FAQs
- → Can I make components of the steak crostini ahead of time?
Yes! You can prepare the horseradish sauce, caramelize the onions, and even grill the steak a day ahead. Store each component separately in the refrigerator. When ready to serve, slice the steak, reheat the onions gently, and assemble on freshly toasted baguette slices.
- → What's the best way to slice steak for crostini?
Always slice steak against the grain (perpendicular to the muscle fibers) to ensure tender bites. For crostini, aim for thin slices about 1/8-inch thick so they're easy to bite through without pulling the entire topping off.
- → Can I substitute the filet mignon with another cut of beef?
Absolutely! While filet mignon offers exceptional tenderness, you can substitute with strip steak, ribeye, or flank steak. If using a tougher cut, consider marinating it first and be especially careful to slice thinly against the grain.
- → How can I adjust the spiciness of the horseradish sauce?
To make the sauce milder, reduce the prepared horseradish to 2-3 tablespoons and increase the sour cream slightly. For a spicier kick, add an extra tablespoon of horseradish or include a pinch of cayenne pepper.
- → What can I serve with steak crostini at a party?
Steak crostini pair wonderfully with other finger foods like stuffed mushrooms, bacon-wrapped dates, or a charcuterie board. For beverages, consider serving a bold red wine like Cabernet Sauvignon, a craft beer, or a whiskey-based cocktail to complement the rich flavors.
- → How do I know when my steak is medium-rare?
The most accurate method is using an instant-read thermometer - medium-rare is 125°F-130°F (52°C-54°C). Visually, the steak should be warm red in the center with a pinkish outer ring. When touched, it should feel similar to the firmness of the base of your thumb when touching your middle finger.