Roasted Vegetable Stock

Preheat oven to 220°C (425°F). Spread all vegetables on two large sheet pans — do not crowd them. Drizzle with oil and toss to coat. Dot the tomato paste in spoonfuls across the vegetables. Roast for 35–40 minutes, tossing once at the 20-minute mark, until the vegetables are deeply caramelized and dark at the edges — golden-brown onions, nearly blackened carrot edges, dark-spotted leeks. The deeper the color here, the richer and more complex the stock.

Remove the pans from the oven. Add a small amount of cold water (about 2 tablespoons per pan) to each hot pan and scrape vigorously with a wooden spoon or spatula to dissolve all the dark caramelized fond from the pan surface. This concentrated caramelized material is extremely rich in Maillard reaction products and is a primary driver of stock depth.

Transfer all roasted vegetables and deglaze liquid to a large stockpot. Add dried mushrooms, herb bundle, peppercorns, and cold water. Bring to a boil, then immediately reduce to a bare simmer — just occasional bubbles breaking the surface. Simmer for 1 hour 30 minutes. Skim any foam that forms in the first 15 minutes. Do not stir — stirring makes the stock cloudy. Do not let it boil hard at any point after the initial come-up.

Set a fine-mesh sieve over a large bowl or pot. Ladle the stock through the sieve — do not pour directly from the pot, which would force cloudy liquid through. Do not press the vegetables. Let gravity drain the stock for 5 minutes. Discard the exhausted vegetables. Allow stock to cool at room temperature for 1 hour, then refrigerate. Skim any oil from the surface when cold. Use within 5 days or freeze in 500ml portions for up to 6 months.