Sprinkle diced tomatoes with 1 tsp of salt, allow to sit in a colander and drain
In a pan, heat oil over medium heat and add onion. Cook until soft. Add in garlic and chili powder and stir for one minute.
Add in one can of black beans, chipotle pepper and 3/4 cup water. Bring to a boil and allow to simmer for 2-3 minutes and reduce.
Place the bean mixture in a food processor along with vinegar and process until smooth. Allow to cool a few minutes.
Add in the remaining beans, tomatoes, corn, half of the cheese and the cilantro. Season with salt and pepper to taste. Mix well and place in a greased baking dish (1.5 qt) Sprinkle with remaining cheese.
Bake for 15 minutes or until heated through, cheese is melted and it is bubbly around the edges. Serve with tortilla chips