Instructions

1. Preheat a large cast-iron skillet over medium-high heat. Once hot, add the ancho and guajillo chiles, and toast, turning as needed, until pliable and fragrant, about 2 minutes. Transfer the chiles to a bowl, and remove and discard their stems and seeds. Add the sesame seeds to the skillet and cook, stirring frequently, until fragrant and toasted, about 2 minutes. Transfer to a separate small bowl.
2. In a medium pot, add the nopales and enough cold water to cover them by 2 inches. Salt generously, add 1 garlic clove and the vinegar, then bring to a boil over medium heat. Lower the heat to maintain a simmer, and cook until the nopales soften, 30–35 minutes. Drain, discarding the cooking liquid, and set aside. Rinse out the pot, then add the potatoes and enough cold water to cover them by 3 inches. Bring to a boil over high heat, then lower the heat to maintain a simmer. Cook until the potatoes are tender when poked with a knife, about 20 minutes. Drain, discarding the liquid.
3. Meanwhile, in a large pot, add the tomatoes, toasted chiles, and enough cold water to cover the vegetables by 2 inches. Bring to a boil over medium-high heat, then cook until the tomatoes are very soft and the chiles are hydrated, about 10 minutes. Use a slotted spoon to transfer the tomatoes and chiles to a blender. Add the toasted sesame seeds, the remaining 2 garlic cloves, the peppercorns, cinnamon, cumin, and some salt to taste, and blend until smooth.
4. In a large pot over medium heat, add the canola oil. Once hot, add the onion and cook, stirring occasionally, until softened and translucent, 8–10 minutes. Stir in the tomato mixture, then bring to a boil. Lower the heat to maintain a simmer, and cook until the onions are very tender and the sauce is thickened slightly, 8–10 minutes more. Stir in the potatoes and nopales, and cook until heated through, 2–3 minutes. Spoon the mole into 6 shallow bowls. Serve with tortillas.