In a medium saucepan, add the cranberries, orange zest, orange juice and water.Cover with a lid, and heat over medium to medium high heat for about 10 minutes.Lift off the lid, and give the cranberries a stir with a wooden spoon, they should be sauce at this point.From here, add in the stevia, tasting as you go to get it to the sweetness level you want.Once you're happy with the level of sweetness, add the vanilla and stir.Allow to cool to room temp. Serve at room temp or if not using, put in an airtight container and keep in the fridge. Unused portions should freeze well.