Make the crema. Combine the sour cream, the milk, and the habanero in a small bowl. Cover and chill until about 15 minutes before serving--it's best not to put super-cold crema into your hot soup.
Fire up a medium-sized saucepan over medium-high heat.
Add the olive oil and swirl.
Add the onion, bell pepper, green chile, cumin, oregano, black pepper, and garlic. Stir and cook for 4 minutes, until the vegetables have softened slightly.
Add the stock and beans, bring to a simmer, and cook 20 minutes.
Add the salt and stir.
Ready a tabletop blender. Fill the blender pitcher halfway with the soup. Remove center piece of blender lid (to allow steam to escape); secure blender lid on blender. Place a clean towel over opening in blender lid (to avoid splatters). Blend the first batch until super-smooth. Pour into a large bowl.
Blend the next batch a bit coarsely. If there's any remaining, don't blend it. Some textural variation is welcome here. (That said, if you like it silken, then blend it all.) Pour the super-smooth batch and the coarse batch back into the saucepan.
Stir and return to a simmer for 3 minutes. Stir in the vinegar.
Serve the soup in shallow bowls, drizzled with the crema.