In a bowl, combine the flour, mesquite or favorite seasoning, cumin, salt and pepper. Toss in the pork until well coated.
Add the oil to a cast iron skillet and warm over medium heat. Add the pork and cook until lightly browned, stirring occasionally. Remove from skillet and set aside.
Place the tomatillos on a baking sheet and bake at 400 degrees F for 15 – 18 minutes or until tender. Remove from oven and let cool slightly.
In a blender add the tomatillos, serrano pepper (to taste), onion, garlic, cilantro, guajillo pepper, and ¼ cup chicken broth. Blend until smooth.
In a stock pot, add the remaining 3 cups chicken broth, pork and green chiles. Stir in the tomatillo sauce. Bring to a boil over medium-high heat for 2 -3 minutes. Reduce the heat and simmer, covered, for 45 minutes – 1 hour or until pork is tender. Salt and pepper to taste.