Place the tomatillos, poblanos and serrano chiles on a baking sheet, then drizzle with 3 tablespoons of the oil and sprinkle some salt and pepper over the top. Place the tomatillos, poblanos and serranos directly over open flames on the grill and cook until the skins are charred and black all over, 2 to 3 minutes per side. Transfer the poblanos and serranos to a large bowl, then cover the bowl with plastic wrap and steam for 2 to 3 minutes. In the meantime, place the tomatillos in a food processor and set aside. Scrape away the charred skins from the poblanos and serranos. Remove the stems and seeds, and roughly chop. Add to the food processor and puree until smooth, about 2 minutes. Set the verde sauce aside for later use.
Preheat the oven to 300 degrees F.
Trim the pork ribs of any excess fat and cube the chicken thighs into large bite-size, about 1 1/2-inch cubes. Sprinkle the pork and chicken with 2 tablespoons salt, the cumin and 1 teaspoon pepper. Place a paella pan or large saute pan over medium-high heat, add the remaining 1 tablespoon olive oil and the chorizo and cook to crisp up and render the fat. Remove the chorizo to a baking sheet and add the pork ribs and chicken thighs to the paella pan. Cook until the pork and chicken turn golden brown, 5 to 7 minutes. Turn the meat over and cook until browned, 5 to 7 minutes, then transfer to the baking sheet with the chorizo. Add the onions and red bell peppers to the pan and saute until the onions are translucent, 5 to 6 minutes. Add the rice and garlic, and mix well until the rice is coated with oil. Cook until the rice smells nutty, 5 to 6 minutes. Add half of the broth and half of the verde sauce, and stir well to combine. Spread the rice evenly around the pan and return the chicken, pork and chorizo to the pan. Cook until the broth is absorbed, about 10 minutes, then add the remaining 3 cups broth. Once bubbling, cover with foil and transfer to the oven; cook until the rice is al dente, 20 to 25 minutes. Remove the foil, dollop the remaining verde sauce over the top and sprinkle with the lime zest and chopped cilantro to serve.