In a saucepan over medium, heat the olive oil then add the onions. Cook the onions until they are translucent (approximately 3 minutes).
Add the chipotle peppers and garlic and stir constantly for 30 seconds until aromatic.
Add the tomato sauce, apple cider vinegar, brown sugar and smoked paprika. Stir constantly until fully combined.
Add the raspberries and bring the mix to a boil. Then lower heat and simmer for approximately 10 minutes. Stir often to break up the raspberries.
Remove sauce from the heat and allow it to cool to room temperature. Use immediately or for best flavor refrigerate overnight to allow the flavors to meld.
Control the heat by lessening the amount of chipotle used. You can cut the chipotles in half and double the smoked paprika used to keep the smoky flavor intact. Smoked paprika is much less spicy than chipotle.