Remove the skin from the mango and cut into small dice. Put the mango into a heavy-based saucepan with the sugar, chill and a tablespoon of water. Bring to a gentle simmer and allow to bubble to a syrupy consistency. The mango should be almost pureed. This will take 8-12 minutes depending on how ripe your mango is.
Add the vinegar and allow the jam to cook for a further minute. Allow to cool and serve either as a glaze for chicken or pork or as an accompaniment for grilled fish, prawns or meat.