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Close up of one steak crostini on slate, the seared crust and pink center of the NY strip visible above the Boursin.
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Steak Crostini with Boursin and Caramelized Onions

This is one of our favorite apps to prep right before a party. Thinly-sliced NY strip goes down on garlicky Boursin while it is still warm, so the cheese softens right where the two meet. Caramelized onions and a stripe of balsamic on top, and you are the reason the tray is empty.
Prep Time30 minutes
Cook Time15 minutes
Resting Time10 minutes
Total Time55 minutes
Course: Appetizer
Cuisine: American
Servings: 24 (1 crostini)
Calories: 111kcal
Author: Brittany Lauren

Equipment

Ingredients

For the Steak

  • 1½ to 2 lb NY strip steak 1 large or 2 small
  • 1 tbsp neutral oil avocado or canola
  • Kosher salt
  • Freshly ground black pepper

For the Crostini

  • 1 baguette sliced into ½-inch rounds
  • 3 tbsp olive oil

Toppings

  • 2 5.2 oz packages Boursin cheese, garlic & herb
  • 2 cups caramelized onions
  • ¼ cup balsamic glaze or thick balsamic reduction
  • ½ cup freshly grated Parmesan cheese
  • 1 cup micro arugula or peppery microgreens
  • Flaky salt
  • Coarse ground black pepper

Instructions

Bring the steak to room temp.

  • Pat it dry. Season generously with salt and pepper. Let it sit for 30 minutes. A dry surface will give you a better crust.
    Two raw NY strip steaks seasoned with kosher salt and cracked black pepper on a slate board, resting before the sear.

Cook the NY strip.

  • Heat a cast iron skillet over high heat until screaming hot. Add a thin layer of oil. Sear the steak 3 to 4 minutes per side, flipping once, until deeply browned. Pull at 125 to 130°F for medium-rare. Rest the steak 10 minutes, then slice it thin, against the grain.
    The rested NY strip steaks on a wood cutting board, one sliced thin against the grain to show a medium rare center.

Toast the baguette.

  • Brush baguette slices lightly with olive oil. Toast under the broiler or in a hot oven until golden and crisp. Cool slightly.
    The same baguette rounds after toasting, golden and crisp at the edges on the parchment lined sheet pan.

Build the crostini

  • Spread a generous layer of Boursin on each crostini. Add a few slices of warm steak. Spoon over caramelized onions. Drizzle lightly with balsamic glaze. Finish with Parmesan, flaky salt, black pepper, and microgreens.
    The finished steak crostini on the sheet pan, showered with shaved Parmesan and microgreens over the balsamic.

Notes

  • Slice the steak while it’s still warm. Warm steak against the Boursin lets the cheese go slightly soft, so it doesn’t sit on the toast like a cold slab.
  • Make-ahead: toast the rounds and caramelize the onions up to a day ahead. Sear the steak within 15 minutes of serving, because sliced steak dries out fast once it hits the air.
  • Double the caramelized onions and freeze half. They thaw in a skillet over low heat in about 5 minutes flat.
  • Don’t crowd the pan. If your skillet is small, sear in two batches so the steak browns instead of steaming.

Nutrition

Serving: 1serving | Calories: 111kcal | Carbohydrates: 8g | Protein: 6g | Fat: 6g | Saturated Fat: 2g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 3g | Trans Fat: 0.003g | Cholesterol: 17mg | Sodium: 112mg | Potassium: 108mg | Fiber: 1g | Sugar: 2g | Vitamin A: 39IU | Vitamin C: 2mg | Calcium: 40mg | Iron: 1mg