Heat a large cast-iron skillet over medium heat. Working in batches, toast chiles on both sides, pressing them down with a metal spatula, until aromatic, about 1 1⁄2 minutes. Transfer chiles to a large bowl, cover with boiling water, weight down with a plate, and let soak, 30 minutes. Drain.
Heat 4 tbsp. of the lard in the skillet over medium-low. Add onions and fry until softened, 5–6 minutes. Add garlic and cook until onions are golden brown, about 18–20 minutes. Remove onions and garlic from skillet with a slotted spoon and transfer to a blender, leaving lard in the skillet. Increase heat to medium, add pork, and cook, turning often, until golden brown on all sides, 12–14 minutes. Transfer pork to a paper towel–lined plate and set aside. Add chicken to the skillet and cook, turning often, until golden brown on all sides, about 10 minutes. Using a slotted spoon, transfer chicken to plate with pork and set aside. Reserve skillet with any remaining lard.
Put peppercorns, cloves, and canela into a mortar and crush with a pestle to a powder. Transfer spices to a blender. Add 1 cup water, drained chiles, and bread and blend until smooth, 2–3 minutes. Strain mixture through a fine-mesh sieve into a medium bowl, pressing on solids with the back of a spoon. Discard solids.
Heat reserved skillet over medium heat, carefully add chile mixture, and fry, stirring constantly, until thickened, 4–5 minutes. Transfer chile mixture to a large heavy pot. Add pork, 2 cups water, vinegar, and salt to taste and stir to combine. Bring to a simmer over medium-high heat, cover, reduce heat to medium-low, and simmer until pork is very tender, about 2 1⁄2 hours. Add chicken and pineapple and cook, covered, until chicken is cooked through, about 20 minutes.
Meanwhile, melt remaining lard in a medium skillet over medium heat. Fry plantains, turning often, until golden brown on all sides, about 5 minutes. Transfer plantains to the mole and stir to combine. Add sugar and salt to taste and continue to cook for 10 minutes more. Serve with corn tortillas, if you like.