Ingredients

• 6 ancho chiles
• 3/4 cup toasted sesame seeds, plus more for garnish
• 5 black peppercorns
• 3 whole cloves
• 1 (1/2-inch) stick Mexican cinnamon (canela)
• 3 1/2 cups chicken broth, homemade or low-sodium canned
• 1 clove garlic, peeled
• 3 tablespoons lard or vegetable oil
• Kosher salt and freshly ground black pepper
• 1 large fresh or dried avocado leaf, toasted and finely ground (optional)
• 2 whole skinless, boneless chicken breasts, halved
• Vegetable oil, as needed
• Mixed cilantro and mint leaves, for garnish

Instructions

1. Stem and seed the chiles, reserving 1 tablespoon of the seeds, or more to taste.
2. Toast the chiles in a large cast iron skillet over high heat. Transfer the chiles to a bowl, cover with hot tap water, and soak for 20 minutes. Drain.
3. Meanwhile, toast the chile seeds in the skillet. In a clean coffee or spice grinder, finely grind the chile seeds, sesame seeds, peppercorns, cloves, and cinnamon.
4. In a blender, combine the chiles, ground spices, 1/2 cup chicken broth, and garlic and blend.
5. Heat the lard in a saucepan over medium-high heat. Pour in the blended sauce and cook, stirring and scraping the bottom, until somewhat reduced, about 10 minutes. Add the remaining 3 cups chicken broth, bring to a boil, lower the heat and simmer until thickened, about 20 minutes more. Season with salt and pepper. (The sauce may be prepared up to 3 days ahead and stored in the refrigerator.)
6. Preheat a grill or grill pan. Lightly brush the chicken with oil and season with salt and pepper. Grill the chicken, turning to make cross-hatched marks, until just cooked through, about 12 minutes. Transfer the chicken to a platter and let rest for 5 minutes.
7. Slice the chicken and transfer to a platter.
8. Reheat the sauce and stir in the avocado leaf. Ladle the sauce over the chicken, sprinkle with sesame seeds, and garnish with herb leaves. Serve with corn tortillas.
9. Serving Suggestion: Warm corn tortillas.