Start a pot over medium high heat, adding in the olive oil. Add in the onion, celery, and carrots, and cook until translucent, about 10 minutes.
Add in the balsamic vinegar to de-glaze the pan for a minute, then add in the tomato paste, dijon mustard, rosemary, cocoa powder, salt, paprika, and pepper. Mix well, and continue to sauté for another two minutes.
Set a crock pot on high, and add in the beans, vegetable mixture, rosemary, beer, and water. Cook the beans for 4 hours, stirring occasionally, until tender. If you don’t have a crock pot, you can simmer the beans in a stock pot, on low heat, until tender.