What cut of steak is best for crostini?

Tender, flavorful cuts that slice thin are ideal, such as flank steak, sirloin, tenderloin, or skirt steak. Ensure it's cooked to a medium-rare for optimal tenderness and ease of slicing.

Can I prepare steak crostini ahead of time?

While the individual components (toasted crostini, cooked steak, horseradish sauce, caramelized onions) can be prepared 1-2 days in advance, it's best to assemble the crostini just before serving to prevent the bread from becoming soggy.

How do you prevent steak crostini from getting soggy?

Toast the crostini until very crisp. Assemble immediately before serving, and ensure the steak and onions aren't excessively juicy directly on the bread. Apply the horseradish sauce as a thinner layer.

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

Slice onions thinly and cook slowly over low-medium heat in olive oil or butter for 30-45 minutes, stirring occasionally, until deeply golden brown and sweet. Avoid high heat, which will burn them. A pinch of salt and a splash of balsamic vinegar towards the end can enhance flavor.

How long do horseradish sauce and caramelized onions last when made in advance?

Homemade horseradish sauce can be stored in an airtight container in the refrigerator for up to 5-7 days. Caramelized onions also keep well in an airtight container in the fridge for about 3-5 days.

What side dishes pair well with Steak Crostini with Horseradish Sauce & Caramelized Onions?

For an appetizer, these are quite rich and complete. If serving as a light meal, a fresh green salad with a vinaigrette, roasted asparagus, or a simple potato gratin would complement the flavors and textures without overpowering them.

Steak Crostini with Horseradish Sauce & Caramelized Onions: An Unforgettable Appetizer 2026

Steak Crostini with Horseradish Sauce & Caramelized Onions

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An elegant, make-ahead appetizer perfect for entertaining. Crisp toasted baguette is topped with sweet caramelized onions, juicy seared steak, and a creamy, zesty horseradish sauce. All components can be prepared in advance for stress-free hosting.

Author: Harmony
Prep Time: 20min
Cook Time: 50min
Total Time: 1h 10min
Yield: About 24 crostini 1x
Category: Snack
Method: broiling, Sautéing
Cuisine: American

Ingredients

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For the Caramelized Onions:
2 large yellow onions, thinly sliced
2 tablespoons unsalted butter
1 tablespoon olive oil
1 teaspoon brown sugar
Pinch of salt
For the Horseradish Sauce:
1/2 cup sour cream
2-3 tablespoons prepared horseradish
1 tablespoon mayonnaise
1 teaspoon fresh lemon juice
1 tablespoon finely chopped fresh chives
Salt and freshly ground black pepper to taste
For the Steak & Assembly:
1 lb flank steak, skirt steak, or sirloin (about 1-inch thick)
1 tablespoon olive oil
Salt and freshly ground black pepper
1 baguette, sliced into 1/2-inch thick pieces
Olive oil, for brushing
Fresh parsley or chives, for garnish

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Instructions

Caramelize the onions: In a large skillet over medium-low heat, melt butter with 1 tbsp olive oil. Add sliced onions and a pinch of salt. Cook, stirring occasionally, for 35-45 minutes until deep golden brown. Stir in brown sugar halfway through if using. Set aside.
Make the sauce: In a small bowl, combine sour cream, horseradish, mayonnaise, lemon juice, and chives. Season with salt and pepper. Cover and refrigerate.
Cook the steak: Pat steak dry and season generously. Heat 1 tbsp olive oil in a heavy skillet over medium-high heat. Sear steak for 4-5 minutes per side for medium-rare. Transfer to a cutting board and let rest 10 minutes.
Toast the bread: Preheat broiler. Arrange baguette slices on a baking sheet, brush with olive oil, and broil 1-2 minutes per side until golden and crisp.
Assemble: Thinly slice the rested steak against the grain. Top each toasted bread slice with caramelized onions, 1-2 slices of steak, a dollop of horseradish sauce, and a garnish of fresh herbs. Serve immediately.

Notes

All components can be made 1-2 days ahead. Store onions and sauce separately in the fridge. Slice steak against the grain for tenderness. Assemble just before serving to keep bread crisp.

Nutrition

Serving Size: 24
Calories: 85
Sugar: 1
Sodium: 120
Fat: 4
Saturated Fat: 1.5
Unsaturated Fat: 2
Trans Fat: 0
Carbohydrates: 7
Fiber: 0.5
Protein: 5
Cholesterol: 15

Find it online: https://harmonymeal.com/steak-crostini-horseradish-sauce-caramelized-onions-3/