Preheat your oven to 400°F.
In a large dutch oven, or cast iron pot, combine the apples, pears, sugar, salt, cider and vinegar. Bring this mixture to a boil, and reduce the heat to a simmer. Partially cover the pot with the lid and simmer for 15 minutes.
Add the lemon juice, cinnamon, ginger and vanilla. Stir to combine.
Using an immersion blender, or a traditional blender, puree the mixture in batches until completely smooth. Return the pureed apple-pear mixture to the pot.
Transfer the pot to the preheated oven and cook for 30 minutes. Carefully, remove the pot from the oven and stir. Continue cooking and stirring in 30 minute increments until the mixture has reduced and thickened. See notes for slow cooker method.
Remove from the oven and fill sterilized mason jars. If canning: can according to manufacturer's instructions. Seal tightly and refrigerate for up to two weeks.