Preheat the oven to <temperature>220<unit>°C</unit></temperature>

Chop <quantity>2<unit>stalks</unit></quantity> of celery

Chop <quantity>⅓</quantity> of a leek

Chop <quantity>2</quantity> medium carrots

Trim, peel, and chop <quantity>2</quantity> medium onions

Transfer all the vegetables to a baking pan. Roast for 25m until deep golden brown

Wrap <quantity>1</quantity> sprig of rosemary, <quantity>3</quantity> sprigs of thyme, and <quantity>2</quantity> bay leaves with a twine. You can use a leek leaf to make a casing

Transfer the roasted vegetables to a pot over medium heat and cover with <quantity>2<unit>L</unit></quantity> of water

Simmer the stock for 2h to extract the flavors

Strain it. The vegetable stock is ready

Use it as a base for soups, risottos or stews.