Stir 2 tablespoons salt into 3 quarts warm water in a large bowl until dissolved. Add the beans, cover with plastic and let sit at room temperature for 8 hours and up to 24. Drain and set aside until ready to use.
Heat a large Dutch oven or large heavy pot over medium heat. Add the bacon and cook, stirring occasionally, until the fat has rendered and the bacon is crispy and deep golden brown, 6 to 8 minutes. Transfer the bacon with a slotted spoon to a small bowl, leaving as much fat in the pot as possible.
Add the chiles, garlic, onions and 4 teaspoons salt to the pot and cook, stirring occasionally, until the vegetables are tender and just beginning to brown, 10 to 12 minutes. Add the tomatoes and cook, stirring occasionally, until the liquid has almost completely evaporated, 3 to 4 minutes. Add the beans, lager, bacon, and 10 cups cold water to the pot and simmer uncovered, stirring and skimming occasionally, adding more boiling water if needed, until the beans are tender, 45 to 75 minutes.
Remove the beans from the heat and stir in the cilantro. Let the beans sit for 10 minutes before serving.