Season the pork meat generously with salt and pepper, lightly flour. Heat oil in a heavy-bottomed skillet over medium high heat and brown pork chunks well in small batches, on all sides. Lift pork out of pan and place in a wide soup pot. Discard fat and place the onions and peppers in the same skillet and sweat over moderate heat, stirring occasionally until limp, about 5 minutes. Add all of the chiles and cook an additional 3-4 minutes, then add the garlic and cook 1-2 minutes more.
Add the Sauteed vegetables, chopped tomatillos, dried herbs and cilantro to the meat, cover with the chicken stock and bring up to a boil and reduce to a slight simmer. Cook for 2-3 hours uncovered or until the pork is fork tender.
Adjust the seasoning to taste with salt and pepper. Serve with red rice for a delightful contrast.