What cut of steak is best for steak crostini?

Lean, tender cuts like flank steak, sirloin, or tenderloin are ideal. They cook quickly and can be sliced very thinly against the grain for maximum tenderness, making them perfect for appetizer portions.

How do I prevent steak crostini from getting soggy?

To prevent sogginess, toast the bread until very crisp and assemble the crostini just before serving. You can also create a barrier with a thin spread of cream cheese or a layer of the caramelized onions directly on the crostini before adding the steak and sauce.

Can steak crostini be made ahead of time?

Components like the caramelized onions, horseradish sauce, and cooked, sliced steak can be prepared 1-2 days in advance and refrigerated. However, for best results, toast the crostini bread and assemble the full appetizers just before serving.

What are the main ingredients in creamy horseradish sauce?

A classic creamy horseradish sauce typically includes prepared or freshly grated horseradish, sour cream or mayonnaise, a touch of vinegar or lemon juice, and seasonings like salt, pepper, and often a pinch of sugar or Dijon mustard.

What's the best way to caramelize onions for crostini?

To caramelize onions properly, slice them thinly and cook them slowly over low to medium-low heat in a pan with a little butter or oil. Stir frequently, allowing them to soften, brown, and sweeten gradually over 30-45 minutes, rather than burning them with high heat.

What are good wine pairings for steak crostini with horseradish and caramelized onions?

A medium-bodied red wine like a Cabernet Franc, Merlot, or a lighter-style Syrah would complement the richness of the steak and sweetness of the onions. For white wine lovers, a dry Riesling or a Grüner Veltliner can cut through the richness and complement the horseradish spice.

Steak Crostini with Horseradish Sauce & Caramelized Onions: The Ultimate Party Appetizer 2026

Steak Crostini with Horseradish Sauce & Caramelized Onions

Print Recipe

5 Stars 4 Stars 3 Stars 2 Stars 1 Star

No reviews

An elegant yet easy party appetizer featuring crispy crostini topped with juicy steak, sweet caramelized onions, and a zesty horseradish cream. Perfect for holiday gatherings or using up leftover steak.

Author: Harmony
Prep Time: 20min
Cook Time: 40min
Total Time: 1h
Yield: Approximately 24 crostini 1x
Category: Snack
Method: Baking, pan-frying, Sautéing
Cuisine: American

Ingredients

Scale

1 large yellow onion, thinly sliced
2 tablespoons unsalted butter
1 tablespoon olive oil
1/2 teaspoon kosher salt
1 teaspoon brown sugar
1 tablespoon balsamic vinegar
1/2 cup sour cream
2-3 tablespoons prepared horseradish
1 tablespoon mayonnaise
1 teaspoon Dijon mustard
1 tablespoon fresh chives, finely chopped
Salt and freshly ground black pepper to taste
1 lb steak (flank, skirt, or sirloin recommended)
1 tablespoon olive oil
Kosher salt and freshly ground black pepper
1 baguette, sliced into 1/2-inch pieces
2-3 tablespoons olive oil, for brushing
Fresh parsley or chives, for garnish

Cook Mode Prevent your screen from going dark

Instructions

Caramelize the onions: Melt butter with olive oil in a large skillet over medium-low heat. Add sliced onions and salt. Cook, stirring occasionally, for 30-40 minutes until deep golden brown. Stir in brown sugar and balsamic vinegar in the last 5 minutes. Set aside to cool.
Make the horseradish sauce: In a small bowl, combine sour cream, horseradish, mayonnaise, Dijon mustard, and chives. Season with salt and pepper. Cover and refrigerate.
Cook the steak: Pat steak dry and season generously with salt and pepper. Heat a skillet over medium-high heat. Add olive oil and sear steak for 3-5 minutes per side for medium-rare. Transfer to a cutting board and let rest 10 minutes, then slice thinly against the grain.
Prepare the crostini: Preheat oven to 375°F. Arrange baguette slices on a baking sheet, brush both sides with olive oil, and bake for 8-12 minutes, flipping halfway, until golden and crisp. Let cool.
Assemble: Spread horseradish sauce on each crostini. Top with steak slices, a tangle of caramelized onions, and a garnish of fresh parsley or chives. Serve immediately.

Notes

All components can be made 1 day ahead. Store onions, sauce, and steak separately in the fridge. Toast crostini and assemble just before serving for maximum crunch. Use leftover steak or a lean cut for a budget-friendly option.

Nutrition

Serving Size: 4
Calories: 85
Sugar: 1
Sodium: 120
Fat: 5
Saturated Fat: 2
Unsaturated Fat: 3
Trans Fat: 0
Carbohydrates: 6
Fiber: 0.5
Protein: 4
Cholesterol: 15

Find it online: https://harmonymeal.com/steak-crostini-horseradish-sauce-caramelized-onions-2/