Steak Crostini with a Creamy Horseradish Sauce and Caramelized Onions
If you're craving a crowd-pleasing appetizer that feels fancy without the fuss, this steak crostini with creamy horseradish sauce and sweet caramelized onions is your golden ticket.
Ingredients
- FOR THE STEAK
- filet mignon or sirloin
- olive oil
- salt and pepper
- fresh rosemary or thyme optional
- FOR THE HORSERADISH SAUCE
- mayonnaise
- prepared horseradish
- Dijon mustard
- lemon juice
- garlic powder
- salt
- FOR THE CARAMELIZED ONIONS
- shallots or yellow onions
- unsalted butter
- brown sugar
- balsamic vinegar
- pinch of salt
- FOR THE CROSTINI BASE
- 1 French baguette
- olive oil for brushing
- flaky sea salt
- TO FINISH
- fresh herbs like chives or parsley
- cracked pepper
Instructions
- 1. Rub steak with olive oil, salt, pepper, and herbs if using. Let it rest at room temperature for 20 to 30 minutes while you prep the other components.
- 2. Whisk mayo, horseradish, Dijon, lemon juice, garlic powder, and a pinch of salt. Chill until ready to use.
- 3. Slice onions thinly and sauté in butter over medium heat. After 10 minutes, add brown sugar and balsamic vinegar. Cook until golden and jammy, about 25 minutes.
- 4. Heat a skillet or grill pan until very hot. Sear steak for 3 to 4 minutes per side for medium-rare. Let rest 10 minutes, then slice thinly against the grain.
- 5. Slice baguette into thin rounds, brush with olive oil, sprinkle salt, and bake at 375°F for 8 to 10 minutes until golden.
- 6. Top each crostini with horseradish cream, steak slice, caramelized onions, herbs, and cracked pepper.
Notes
You can make the sauce and onions up to 2 days in advance.
Toast crostini the night before and store airtight.
Always slice steak thinly and against the grain for tenderness.
Swap horseradish cream with garlic aioli or whipped feta if desired.