Ingredients:

  • 2 tablespoons (30ml) olive oil
  • 1 medium yellow onion, finely chopped (about 1 cup / 150g)
  • 2 medium shallots, finely chopped (about 1/2 cup / 75g)
  • 2 cloves garlic, minced
  • 1 teaspoon dried thyme
  • 1 bay leaf
  • 1/2 cup (120ml) dry red wine, preferably Bordeaux (Cabernet Sauvignon or Merlot also work well)
  • 4 cups (950ml) beef broth (low sodium preferred)
  • 1 tablespoon (15ml) balsamic vinegar
  • 2 tablespoons (30g) unsalted butter, cold and cut into small cubes
  • 1/4 cup chopped fresh parsley (optional, for garnish)
  • Salt and freshly ground black pepper to taste
  • 2 pieces beef marrow bones (about 4 inches long), soaked in cold water for 24 hours, changing the water several times

Instructions:

  1. If using marrow, gently simmer the marrow bones in water for about 10 minutes until softened. Remove marrow from bones with a knife or spoon. Set aside.
  2. Heat olive oil in a saucepan over medium heat. Add onion and shallots and cook until softened, about 5-7 minutes. Add garlic, thyme, and bay leaf; cook for 1 minute more, until fragrant.
  3. Pour in the red wine and bring to a simmer, scraping up any browned bits from the bottom of the pan (fond). Reduce the wine by about half, until syrupy.
  4. Pour in the beef broth and bring to a simmer. Reduce the heat to low and simmer gently for 30-40 minutes, or until the sauce has reduced by about half and thickened slightly. Skim off any scum.
  5. Strain the sauce through a fine-mesh sieve into a clean saucepan, discarding the solids. Stir in the balsamic vinegar. Taste and adjust seasoning with salt and pepper.
  6. Reduce the heat to very low. Whisk in the cold butter, one cube at a time, until the sauce is smooth and glossy.
  7. If using, gently stir in the poached marrow.
  8. Garnish with chopped fresh parsley, if desired. Serve the borderlaise immediately.