Briefly toast the opened ancho chiles in a dry skillet over medium heat, about 10 seconds per side, just until fragrant. Do not blacken. Cover with hot water in a bowl for 15 minutes, then drain and discard the soaking water.

In the same dry skillet, cook tomatoes cut-side down and onion wedges over medium heat for 7–9 minutes, turning as they develop browned patches. Add garlic for the final 2 minutes. Transfer to a plate and let cool until warm, not steaming.

Pat the chicken dry without rinsing it. Season with half the salt. Heat oil in the skillet over medium-high heat. Brown thighs in two batches for about 3 minutes per side; transfer to a clean plate. They are not cooked through yet.

Blend the warm vegetables, drained chiles, peanuts except the reserved tablespoon, 500 ml water, cumin, oregano, cinnamon and remaining salt until very smooth. Never seal steaming ingredients in a blender; let them cool first and follow the blender’s hot-liquid instructions.

Pour sauce into the skillet carefully and stir over medium-low heat for 5 minutes. Return chicken and accumulated juices. Cover partly and simmer gently for 18–25 minutes, turning once and stirring the sauce around the pieces. Add water a splash at a time if it catches or becomes paste-like. Every thigh must reach at least 165°F (74°C) in its thickest part; continue cooking if necessary.

Taste the cooked sauce and adjust seasoning if needed. Divide chicken and sauce into six equal servings. Sprinkle with reserved peanuts and optional cilantro. Rice and tortillas are optional sides, not included in the nutrition estimate.