Fire-roast the peppers and tomatillos. You can do this on the grill, over a gas burner, or under your broiler turned on high. The goal is to char the skin of the vegetable. ROASTING THE PEPPERS AND TOMATILLOS ADDS TONS OF FLAVOR TO THEM! IT IS WORK BUT DO NOT SKIP THIS STEP!
Place the charred vegetables in a large heat proof bowl or pan and cover with foil. The steam from the vegetables will help the charred skin come off easily. Let sit covered 15-20 minutes and then the charred skin will easily peel off the peppers and tomatillos.
In a large (6 to 8 quart) stock pot, over high heat, brown the bacon reserving the bacon drippings.
Next, trim off any excess fat from the pork and cut into 1 inch squares. Liberally season the pork with salt and pepper and toss with flour to coat evenly.
DO NOT SKIP THIS STEP! THIS IS WHAT ADDS THE MOST FLAVOR TO THE CHILI VERDE! Brown the seasoned pork in small batches, in the bacon drippings, being careful not to overcrowd the pot. Remove the pork from the pot and pour off the fat drippings, leaving two tablespoons of fat. Caramelizing the meat to a rich golden-brown is a key flavor step!
In the same pot, over a medium heat, add the chopped onion, garlic, salt, and pepper and sauté until transparent, scraping up any browned bits. Add the cumin, pork, and chicken stock, and cook simmering over medium-low heat for 1 hour.
Place half of the peppers, one bunch of cilantro, and half of the tomatillos in to a blender or the bowl of a food processor and pulse for a chunky puree. Add the puree to the pot with the pork and stir to combine, cooking on medium-low for an additional 30 minutes.
Roughly chop the remaining tomatillos, peppers, and cilantro. Add them to the pot, stir, and simmer for an additional 30 minutes, for a total cooking time of two hours.
Add the lime juice and adjust seasoning to taste with salt and pepper.