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one croissant sandwich with thin warm roast beef slices, soft golden-brown caramelized onion strands and a thick pale horseradish sour-cream spread, without cheese or raw greens
Melissa Hart

Roast Beef and Horseradish Croissants

Roast the beef as a small whole piece and slice it across the grain after resting, because warm thin slices are easier to tuck into the croissant than thick slabs cut too soon. The onions take their time in a separate skillet, turning soft and sweet enough to balance a sharp horseradish sour cream without needing a layer of cheese. Use prepared horseradish that lists grated root rather than a creamy sandwich sauce, then drain it before measuring so the spread stays thick. This is a weekend lunch with a little cooking involved, but the hands-off roast gives you time to finish the onions and warm the pastry before assembling.
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Prep Time 20 minutes
Cook Time 1 hour 15 minutes
Total Time 1 hour 35 minutes
Servings: 4
Ingredients Method

Ingredients
  

  • 1 1/4 lb boneless beef top round roast trimmed
  • 1 tbsp olive oil divided
  • 3/4 tsp fine salt divided
  • 1/2 tsp black pepper divided
  • 2 medium yellow onions thinly sliced
  • 1 tbsp unsalted butter
  • 2 tbsp water plus 2 tbsp if needed for onions
  • 1/3 cup sour cream
  • 1 1/2 tbsp prepared grated horseradish drained
  • 1 tsp Dijon mustard
  • 4 large plain croissants about 3 oz each, split

Method
 

  1. Heat oven to 375°F. Rub beef with 1 teaspoon oil, 1/2 teaspoon salt and 1/4 teaspoon pepper and place in a small roasting pan. Roast for 40 to 55 minutes, checking early, until the thickest center reaches 145°F.
  2. Meanwhile, melt butter with the remaining 2 teaspoons oil in a skillet over medium-low heat. Add onions and the remaining 1/4 teaspoon salt and cook for 30 to 40 minutes, stirring often, until deeply golden and soft.
  3. Add 2 tablespoons water to the onions and scrape up browned bits. Cook until the liquid evaporates, adding the optional 2 tablespoons water only if the pan begins to scorch before the onions soften.
  4. Rest the roast for at least 10 minutes before slicing very thinly across the grain. Mix sour cream, horseradish, mustard and the remaining pepper.
  5. Reduce oven to 300°F and warm split croissants cut-side up for 5 minutes. Spread horseradish cream over their cut faces.
  6. Divide warm beef and caramelized onions among the bottoms. Close with the tops and serve promptly.