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Thinly sliced medium-rare roast beef topped with rich mushroom and leek sauce on a rustic ceramic plate, served with crusty Italian bread and fresh herbs.

Mushroom and Leek Sauce for Roast Beef

A rich, creamy mushroom and leek sauce rooted in Northern Italian tradition. This recipe elevates roast beef with earthy porcini mushrooms, sweet leeks, and herbs, perfect for Sunday dinners or special occasions.
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Prep Time 30 minutes
Cook Time 1 hour 30 minutes
Resting Time 20 minutes
Total Time 2 hours
Course Main Course
Cuisine American/Italian Fusion
Servings 6 servings
Calories 640 kcal

Equipment

  • Roasting Pan
  • Large Skillet
  • Fine-mesh Sieve

Ingredients
  

For the Roast Beef

  • 1.5 kg beef roast preferably ribeye or sirloin
  • 3 tbsp extra virgin olive oil
  • 4 cloves garlic peeled and lightly crushed
  • 3 sprigs fresh rosemary
  • salt and freshly ground black pepper to taste

For the Mushroom and Leek Sauce

  • 30 g dried porcini mushrooms
  • 250 g fresh cremini mushrooms sliced
  • 2 large leeks white and light green parts only, thinly sliced
  • 3 tbsp unsalted butter
  • 2 tbsp extra virgin olive oil
  • 2 cloves garlic minced
  • 120 ml dry white wine Pinot Grigio preferred
  • 240 ml beef stock
  • 120 ml heavy cream
  • 1 tbsp fresh thyme leaves
  • 1 tbsp fresh flat-leaf parsley finely chopped
  • 1 tsp fresh rosemary finely chopped
  • salt and freshly ground black pepper to taste
  • 1 tbsp all-purpose flour optional, for thickening

Instructions
 

  • Bring beef to room temperature. Pat dry, rub with olive oil, and season with salt and pepper.
  • Preheat oven to 190°C (375°F). Sear beef on all sides in a hot skillet until deeply browned.
  • Transfer beef to roasting pan with garlic and rosemary. Roast for 15 minutes per 500g for medium-rare or until 55°C (130°F) internally.
  • Let beef rest 20–30 minutes before slicing to retain juices.
  • Soak porcini mushrooms in hot water for 20 minutes. Strain and reserve liquid. Chop mushrooms.
  • Clean and slice leeks. Sauté leeks in butter and oil over medium heat until soft, about 5–7 minutes.
  • Add cremini mushrooms and cook until browned, about 8–10 minutes. Add garlic and porcini, cook 1–2 more minutes.
  • Deglaze with wine, scraping pan. Reduce by half. Add reserved soaking liquid, stock, and thyme. Simmer 10–12 minutes.
  • Reduce heat, stir in cream and optional flour. Simmer 5 minutes. Finish with parsley and rosemary. Season to taste.

Notes

The sauce can be made ahead and improves in flavor overnight. Great for freezing. Serve with rosemary potatoes and arugula salad.
Keyword Beef, Italian-American cuisine, mushroom sauce