Blanch the peaches. when cool enough to handle, slip off their skins. Remove the pits, chop the flesh & set aside.
Heat oil in a medium sized saucepan. Add the onion & saute until golden. Add the peaches & remaining ingredients, except for the mint. Cover & cook over low heat for about 20 minutes. The mixture should be thick with reduced liquid.
Stir in the mint & cook over low heat for 10 minutes. Allow to cool to room temperature before serving. Refrigerate unused portion in an airtight container for up to 2 weeks. Serve with curries or grain dishes.