Duck served in Tlaxcala's dark, earthy mole prieto made with dried corn and beans. This high protein, carnivore-worthy family dish pairs rich duck with one of Mexico's most unique sauces.
Soak the dried beans and dried corn separately overnight in plenty of water; drain and set aside.
Place the duck legs in a pot with water to cover, half the onion, and 2 garlic cloves; bring to a simmer, skimming off any foam, and cook gently for 60 minutes until just tender.
In a separate pot, simmer beans and corn with fresh water, 1 tbsp epazote, and a pinch of salt over medium heat. Cook, partially covered, for 1.5–2 hours until tender.
Toast pasilla and ancho chiles over medium-high heat in a dry skillet until fragrant and darkened but not burnt, about 1–2 minutes per side. Remove and soak chiles in hot water for 15 minutes.
In a blender, combine rehydrated chiles, remaining garlic and onion, 1 tbsp lard, and cooked beans and corn. Blend until very smooth, adding a bit of duck broth if needed.
Heat 2 tbsp lard in a large Dutch oven over medium heat; add the chile-bean-corn mixture. Stir and cook for 10–12 minutes, letting it deepen in color while stirring frequently to prevent scorching.
Add the duck pieces into the mole, ladling in about 2 cups of duck broth. Season with sea salt, black pepper, and remaining epazote. Simmer gently for 15–20 minutes so the duck is heated through and flavors meld.
Adjust consistency with more broth if needed. Taste and adjust seasoning before serving.