• Rinse beans in a colander and pick through, discarding any debris or small stones. Place in a medium saucepan and add enough water to cover beans. Bring to a boil over high heat and cook for 2 minutes. Turn off heat and let beans rest for 1 hour. Drain beans in a colander and rinse. Wash saucepan, return beans to saucepan and add enough water to cover by 2 inches. Bring to a boil over high heat. Reduce heat to low to maintain a steady simmer. Cover and cook for 1½ to 2 hours or until beans are very tender. Reserve about 2/3 cup cooking liquid, drain beans and set aside to cool. (Or, cover and refrigerate beans in their cooking liquid for up to 4 days. Reserve 2/3 cup liquid and drain before proceeding with recipe.)
• In a medium bowl, combine tomatoes, onion, jalapeños and about two-thirds of cilantro. Squeeze juice of 1 lime over tomato mixture and season, to taste, with salt and black pepper. Set aside.
• In a food processor or blender, combine avocados, remaining cilantro and remaining juice of 1 lime. Purée until slightly chunky. Season with salt and black pepper, to taste. Set aside.
• Place beans and 1/3 cup reserved cooking liquid in a food processor (or use a powerful blender or mash by hand with a potato masher). Process until you have a slightly chunky purée, adding additional cooking liquid, 1 tbsp at a time, as needed to reach desired consistency. Add 1/2 tsp salt and black pepper. Pulse several times to combine.

Putting It All Together

• Transfer beans to a 9 x 13-inch casserole dish or large glass bowl and spread into an even layer.
• Sprinkle cheese evenly over beans. Dollop scoops of avocado mixture over cheese and use a spatula to spread into a thin layer. Dollop scoops of sour cream over avocado and spread into a thin layer. With a slotted spoon (to drain any liquid), spread tomato mixture evenly over sour cream. Serve immediately or cover and chill for up to 4 hours.