Ingredients:

  • 3 large yellow onions (350g), skins on, quartered
  • 4 large carrots (400g), unpeeled, cut into 2-inch chunks
  • 5 stalks celery (300g), including leaves, chopped
  • 1 large leek (200g), white and light green parts, cleaned and sliced
  • 1 head of garlic, halved crosswise
  • 2 tablespoons (32g) tomato paste
  • 0.5 cup (15g) dried shiitake mushrooms
  • 1 bunch fresh parsley, stems and leaves
  • 4 sprigs fresh thyme
  • 2 dried bay leaves
  • 1 teaspoon (5g) whole black peppercorns
  • 2 tablespoons (30ml) neutral oil
  • 3.5 liters cold filtered water
  • 1 piece Kombu (dried seaweed)

Instructions:

  1. Preheat your oven to 425°F (220°C).
  2. Toss the onions, carrots, celery, and garlic with 2 tablespoons of neutral oil on a rimmed baking sheet.
  3. Roast for 25–30 minutes, turning once, until the edges are dark brown and the vegetables are caramelized.
  4. In the last 5 minutes of roasting, smear the tomato paste onto a corner of the tray to let it darken and cook out.
  5. Transfer all roasted vegetables and the tomato paste into a large heavy-bottomed stockpot. Deglaze the baking sheet with a splash of water to scrape up any browned bits (fond) and add to the pot.
  6. Add the dried mushrooms, parsley, thyme, bay leaves, peppercorns, kombu, and 3.5 liters of cold filtered water.
  7. Bring to a low simmer over medium-high heat, then reduce heat to maintain a very gentle bubble. Simmer for 60 to 90 minutes. Avoid boiling vigorously to prevent cloudiness.
  8. Strain the broth through a fine-mesh strainer lined with cheesecloth into a clean container. Discard solids.