Preparation

• Put one-third of the beans into the bowl of a food processor, along with the tomatoes and their juices, chipotle, and adobo sauce. Process until smooth and set aside.
• Heat the oil in a 5- to 6-quart Dutch oven or similar heavy-duty pot over medium-high heat until it’s shimmering hot, about 2 min. Add the beef, season with 1/2 tsp. salt, and cook, using a wooden spoon to break up the meat, until it loses its raw color, about 3 minutes. Transfer the beef to a large plate using a slotted spoon. Add half of the onion and 1/4 tsp. salt, and cook, stirring, until it begins to brown and soften, about 3 min. Reduce the heat to medium. Add the chili powder and cumin and cook for 20 seconds. Add the remaining black beans, the puréed bean mixture, and the beef to the pot and simmer for 10 min., stirring frequently. Add half of the lime juice, half of the cilantro, and salt and pepper to taste. If the chili is thicker than you like, it may be thinned with water.
• Meanwhile, in a small bowl, mix the remaining lime juice and onion with the avocado. Season generously with salt and pepper. Serve the chili topped with the avocado mixture and remaining cilantro.

Coarsely crumble about 3 handfuls of tortilla chips in a zip-top bag, and use them as an additional chili topping.