Add sugar and leave a minute to caramelize and then Madeira, balsamic vinegar and water. Bring the sauce to a boil and then reduce heat to simmer.
Add veal stock, whisk and let simmer for 3-5 minutes.
Strain to get rid of solids and return liquid to the saucepan.
Either whisk in the cornstarch and bring to a boil until thickens or;
Reduce until thick enough to coat the back of a metal spoon. This will take roughly 20 minutes but will maintain a darker color and give more depth to the flavor.
Taste and adjust seasoning with salt and pepper. Add butter and a few more drops of Madeira.
Refrigerate for up to 5 days, or freeze for up to 3 months.