- With the rack in the middle position, preheat the oven to 400°F (200°C).
- On a baking sheet, toss the vegetables with the oil. Bake for 1 hour or until the vegetables are golden brown, stirring frequently. Remove from the oven. Sprinkle the flour over the vegetables and stir in the tomato paste until thoroughly combined. Continue baking for 10 minutes.
- Place the vegetables in a large pot. Pour the wine onto the baking sheet and scrape up any browned bits. Add the wine mixture to the vegetables along with the bouquet garni and water. Bring to a boil, then simmer for 1 hour.
- Strain the stock through a sieve into another pot, pressing the vegetables with the back of a ladle to extract all the juices. Over high heat, boil for 10 minutes or until reduced by half, stirring occasionally. Season with salt and pepper.
- Use the demi-glace as a sauce for vegetables, risotto and pasta, or even fish or meat.
To make a bouquet garni, bundle the herbs and aromatics and tie together with kitchen string.