Place beans in a Dutch oven; add water to cover by 2 in. Bring to a boil; boil for 2 minutes. Remove from the heat; cover and let stand for 1 hour.
Place peppers on a baking sheet; broil 4 in. from the heat until skins blister, about 4 minutes. With tongs, rotate peppers a quarter turn. Broil and rotate until all sides are blistered and blackened. Immediately place peppers in a bowl; cover and let stand for 15 minutes. Peel off and discard charred skin. Remove stems and seeds. Chop peppers and set aside.
Drain and rinse pinto beans, discarding liquid. Return beans to the Dutch oven. Add 6 cups water and bay leaf; bring to a boil. Reduce heat; simmer, uncovered, for 1-1/2 to 2 hours or until beans are tender.
Meanwhile, crumble chorizo into a skillet; cook over medium heat for 6-8 minutes or until fully cooked. Drain and set aside. In the same skillet, melt lard. Add onion and reserved peppers; cook and stir until tender, about 5 minutes.
Add the chorizo, pepper mixture and salt to beans. Simmer, uncovered, for 30 minutes. Discard bay leaf. Just before serving, stir in cilantro.