- Bring the stock to a boil in a saucepan and taste. If it lacks body, reduce it until concentrated. In a cup, mix the arrowroot or potato starch to a thin paste with the Madeira or water.
- Whisk the paste into the boiling stock, which will thicken at once. Add only enough paste to thicken the sauce to the required consistency. Whisk in tomato paste, if using, add