Bring red wine vinegar and sugar to boil in a medium heavy sauce pan over medium heat. Continue cooking until sugar has carmelized, 10-15 minutes. (Watch carefully, because sugar burns easilyl.)When caramalized, add Madeira; stir well until mixture has dissolved.

Add stock or water and vanilla beans. Reduce heat to low. Simmer until the mixture has been reduced by one half. Remove from heat; let stand at lease 1 hour.

When ready to use, remove vanilla beans. Reheat mixture over low heat, bringing to simmer.

Mix cornstarch and water; add to sauce. Simmer until thick, about 3 minutes. Glaze meat before cooking; add as needed.