Roast the Veggies: Preheat your oven to 450°F (230°C). Place the tomatillos, green chiles, onion, and garlic on a baking sheet. Roast for about 20 minutes, or until they are blistered and slightly charred.
Blend the Sauce: Once roasted, transfer the tomatillos, chiles, onion, and garlic to a blender. Add a splash of chicken broth and blend until smooth.
Cook the Chicken: In a large pot, heat a bit of oil over medium-high heat. Add the chicken pieces and season with salt and pepper. Sauté until browned, about 5-7 minutes.
Combine and Simmer: Pour the blended chile sauce over the chicken and add the remaining chicken broth, cumin, and oregano. Bring to a boil, then reduce the heat to low and let it simmer for about 30 minutes, or until the chicken is tender and the flavors meld.
Serve: Garnish with fresh cilantro and serve with warm corn tortillas for a complete meal.