Instructions:
- Poach the Chicken: Place chicken, water/broth, onion quarters, smashed garlic, and 1 tsp salt in a pot. Bring to a simmer, skim any foam, and cook until fully cooked (internal temp 165°F/74°C). Remove chicken, reserving 1/2 cup of the cooking liquid. Let chicken cool slightly, then shred finely.
- Sauté Aromatics: Heat oil in a large skillet. Add the thinly sliced white onion and cook over medium heat until softened and slightly translucent (about 8–10 minutes). Add minced garlic and cook for 1 minute until fragrant.
- Prepare the Sauce: While onions cook, combine the drained diced tomatoes, chipotle peppers, adobo sauce, oregano, cumin, and 1/4 tsp salt in a blender. Add the 1/2 cup of reserved chicken broth. Blend until completely smooth.
- Simmer the Sauce: Pour the blended sauce over the softened onions in the skillet. Bring to a gentle simmer. Cook for 5–7 minutes, allowing the sauce to deepen in colour and slightly thicken.
- Combine and Finish: Add the shredded chicken to the simmering sauce. Toss well to ensure every piece is coated. Reduce heat to low and cook for another 10 minutes, stirring occasionally, until the chicken has fully absorbed the sauce. Taste and adjust seasoning.
- Serve: Garnish generously with fresh cilantro. Serve hot over tostadas or rice.