In a skillet cook the bacon pieces several minutes, stirring often, until bacon starts to brown and renders its fat. Add the onion and cook until golden, about 6-8 minutes. Add the jalapeños and cook for 1 minute, then add garlic until garlic becomes fragrant. About 1 minute.
Transfer the mixture from the skillet to the slow cooker and add the beans. Cover with 7 cups of water. Add the lard. Drop in the dried chile peppers. Cook on high 3 - 4 hours. Cooking time will depend on the freshness of the beans.
Add the tomatoes and continue to cook for 30 minutes or until tomatoes are hot.
Remove 2 cups of the beans and process in a blender or food processor until smooth. Add the smooth beans back to pot and stir in the cilantro. Taste and season with salt. Remove the dried chile peppers. Ladle into bowls and serve.
Notes
Before placing beans in the crockpot, sort through them and remove any that look dark and dried up. Pro Tip: Remove about 2 cups of the beans and process in a blender or food processor. Return the beans to the crockpot for a creamier and thicker end result.Buying Beans: Whenever possible purchase dried beans from the bulk section rather than bags of beans on the shelf. There's just no way to tell how old they are and you risk purchasing beans that just won't soften up as well when they cook.