Ingredients:

  • 2 large onions, quartered, skins left on (300g)
  • 3 large carrots, cut into large chunks (200g)
  • 3 stalks celery, cut into chunks (120g)
  • 1 head of garlic, whole (50g)
  • 2 tbsp olive oil (30ml)
  • 2 tbsp tomato paste (32g)
  • 12 cups cold filtered water (2.8L)
  • 1 tbsp black peppercorns, whole (3g)
  • 3 sprigs fresh thyme (3g)
  • 2 bay leaves
  • 1 tsp salt (5g)

Instructions:

  1. Preheat your oven to 450°F (230°C). Toss the onions, carrots, celery, and whole head of garlic in olive oil and spread them on a large rimmed baking sheet.
  2. Roast for 30–40 minutes, stirring once halfway through, until edges are charred and mahogany-colored.
  3. In the last 5 minutes of roasting, dollop the tomato paste over the vegetables and stir to toast the paste.
  4. Transfer all roasted vegetables and any browned bits from the pan into a heavy-bottomed stockpot or Dutch oven.
  5. Add the cold filtered water, peppercorns, thyme, and bay leaves. Bring to a gentle boil, then immediately reduce to a low simmer.
  6. Simmer for 45–60 minutes, ensuring the liquid barely bubbles.
  7. Turn off the heat. Use a colander to remove the large vegetable chunks, then pass the remaining liquid through a fine-mesh strainer into a clean pot or jar.