Mole Negro

Wipe chiles with a damp cloth. Using kitchen scissors, cut a slit lengthwise along 1 side. Open chiles up and remove seeds, veins, and stems; discard stems. Toast seeds and veins in a dry large skillet, preferably cast iron, tossing occasionally, until completely blackened, 7–9 minutes; set aside.

Working in batches, toast chiles, turning occasionally, until slightly darkened and blistered but not burnt, about 1 minute per side. Transfer chiles to a medium bowl and add boiling water to cover (at least 2 ½ cups). Let soak until chiles are softened, about 20 minutes.

Meanwhile, cook tomato, onion, tomatillos, and garlic in same skillet over medium heat, turning occasionally, until almost completely blackened, 10–15 minutes. Let cool slightly, then remove skin from tomato; discard. Transfer tomato, onion, tomatillos, and garlic to a blender. Add ½ cup broth and purée until smooth; set tomato purée aside.

Heat 1 tablespoon oil in same skillet. Add plantain and cook, stirring occasionally, until golden brown, about 5 minutes. Set half of plantain aside for serving; place remaining plantain in a medium bowl.

Wipe out skillet and toast almonds, pecans, and peanuts in skillet, stirring often, until golden brown and fragrant, about 5 minutes. Transfer to bowl with plantain.

Toast breadcrumbs in skillet, tossing often, until golden brown, about 2 minutes; transfer to bowl.

Toast cinnamon sticks, allspice, cloves, raisins, pumpkin seeds, sesame seeds, dried herbs, aniseed, and cumin seeds until spices are fragrant, about 4 minutes; transfer to bowl.

Working in 2 batches, purée plantain mixture, adding 1 cup broth to each batch, until very smooth. Transfer plantain purée back to bowl; set aside.

Drain chiles, reserving soaking liquid. Purée chiles and 1 ½ cups soaking liquid in clean blender, adding more soaking liquid as needed, until smooth. Add toasted seeds and ribs and blend until smooth. Strain chile purée through a fine-mesh sieve into a medium bowl.

Heat remaining 2 Tbsp. oil in a large Dutch oven or other heavy pot over medium. Cook chile purée, stirring constantly, until reduced by about one-third, 15–20 minutes. Add reserved tomato purée and cook, stirring often, until thickened, 8–10 minutes (reduce heat if needed to keep mixture from splattering). Add reserved plantain purée and simmer, stirring often, until thickened, 8–10 minutes. Stir in remaining 1 cup soaking liquid and bring to a boil. Reduce heat and simmer, stirring occasionally, 20 minutes.

Add chocolate and stir until melted. Return mole to a simmer and cook, stirring occasionally and adding broth by the cupful, until mole is just thick enough to coat spoon, about 30 minutes. Add sugar to taste and season with salt. Serve with meat or fish of choice.

DO AHEAD: Mole can be made 1 week ahead. Let cool; cover and chill. Reheat, adding broth as needed to loosen.