Preheat saucepan to medium heat, and add olive oil. Once oil is hot, add garlic and onions and sauté for 4-5 minutes, or until translucent. Add brown sugar and white vinegar, and cook until melted.
Add chipotle puree and crushed pineapple, and bring to a simmer. Simmer on low heat for 15-20 minutes.
Remove from heat, and let cool for 10 minutes. Puree in blender or with immersion blender.
Once ribs are tender (they should come apart easily but not fall apart), remove from oven. Turn heat up to 375°F. Unwrap foil and discard, then brush ribs generously with chipotle pineapple BBQ sauce.
Bake for 20-30 minutes and apply more BBQ sauce every 10 minutes. This stage can also be done on a grill!