Heat oil in a medium skillet. Once oil is hot, add in onion and cook until onion is caramelized, about 20-30 minutes. If onions starts to cook too quickly, add a little water to the skillet and continue to cook until soft and brown.

In a medium bowl combine onion, black beans, smoked paprika, chili powder, salsa, green chiles, and chipotle paste. Place the pinto beans in a 1 ½-quart slow cooker, and mash them with the back of a wooden spoon or potato masher. Top with black bean mixture, and sprinkle with cheese.

Cover and cook on low for 3-4 hours or on high for 2 hours, or until hot and bubbly.

Serve immediately or keep warm, covered, on low for up to 2 hours. Serve with sweet potato chips, tortilla chips, or fresh sliced veggies.