Place the cranberries in a heavy bottom pan with 1, 3/4 cups water and heat until the cranberry skins start to pop open.

Add the sugar, lemon and orange zests, juices and diced apple. Cook at a simmer for a further 15 minutes.

Remove from heat, allow to cool a little before storing for up to 5 days in the fridge. The sauce becomes thicker as it sits in the fridge.