Combine apples, cranberries, orange juice and zest, and vanilla bean in a large stock pot over medium heat. Cover and cook for 15 minutes or until boiling, stirring every few minutes. Carefully remove vanilla bean pod.

Reduce heat to low and use an immersion blender to crush the cranberries and apples. This creates a velvety-smooth texture. You can mash the mixture with a potato masher, too, but it will not produce the smooth texture. Alternatively, transfer to a blender at the end of cooking to achieve desired consistency.

Stir in sugar if using. Continue simmering another 5 minutes as the sauce cools. The texture should be quite thick and will continue to thicken as it cools.

At this point, you can transfer the mixture to mason jars if canning, or transfer to an airtight container and refrigerate until needed. This sauce keeps well for up to 5 days in the refrigerator, so I like to make it in advance. Alternatively, it does freeze and thaw very well too.