Roast Beef & Onion Canapés are the kind of appetizer that make you look like you tried harder than you did. Crispy crostini layered with melty Gruyère, tender roast beef, sweet caramelized onions, and a punchy remoulade sauce hit all the right notes. These little bites are rich, savory, and full of flavor. Perfect for a cocktail party or holiday tray.

If you like appetizers with layers of flavor, this one’s worth making. The sweet onions balance the sharp horseradish and Dijon, and the Cajun seasoning adds a subtle kick that keeps you going back for another. You can make the components ahead of time, which makes assembling them a breeze right before serving.

Helpful Tips

Don’t rush the onions: Low and slow is the way to go for caramelized onions. Give them time to get that deep, sweet flavor.
Use a serrated knife for the baguette: It helps get clean slices without crushing the bread.
Make the remoulade ahead: The sauce gets even better after a few hours in the fridge, so mix it early and let those flavors meld.

Roast Beef & Caramelized Onion Canapes

Crispy crostini layered with melty Gruyère, tender roast beef, sweet caramelized onions, and a punchy remoulade sauce hit all the right notes.

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Prep Time 15

Cook Time 30

Total Time 45

Course Appetizer

Cuisine American

Servings crostini

Calories 143 kcal

Ingredients

1 large onion thinly sliced
1 tablespoon olive oil
½ baguette sliced (12 slices)
½ pound deli sliced roast beef sliced
1 cup gruyere thinly sliced
¼ cup mayonnaise
1 teaspoon Dijon mustard
1 1/2 teaspoon horseradish
½ teaspoon Cajun seasoning
1 teaspoon hot sauce
¼ teaspoon Worcestershire sauce
3-4 sprigs fresh thyme for garnish

Instructions

Preheat the oven to 325°F.
Add the olive oil to a large skillet over medium heat. Add the onions to the skillet and cook for 25-30 minutes, until caramelized.
Spray or brush the baguette slices with olive oil. Set them on a baking sheet. Top with a slice of gruyere. Bake for 8 minutes, until the bread is crispy.
To make the remoulade sauce, add the mayonnaise, Dijon, horseradish, Cajun seasoning, hot sauce, and Worcestershire sauce. Whisk until smooth.
When the crostini are done, add a slice of roast beef, then some carmelized onions. Top with the remoulade and garnish with thyme leaves.

Notes

You will likely have leftover sauce. If you don’t want that, you should cut the sauce recipe in half.

Nutrition

Calories: 143kcalCarbohydrates: 7gProtein: 9gFat: 9gSaturated Fat: 3gPolyunsaturated Fat: 3gMonounsaturated Fat: 3gTrans Fat: 0.01gCholesterol: 25mgSodium: 475mgPotassium: 101mgFiber: 1gSugar: 1gVitamin A: 161IUVitamin C: 10mgCalcium: 180mgIron: 1mg

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