Pull off the husks of the tomatillos and give them a good rinse. I usually de-stem them but this is optional. Add the tomatillos to a roasting pan along with the rinsed poblanos and roast them in the oven at 400F. I usually flip the poblanos over after 15-20 minutes, and if the tomatillos are disintegrating you can take them out of the oven at this point. The poblanos will need about 30 minutes total to fully roast.
Once the poblanos and tomatillos are in the oven I usually start working on the meat, but here are the remaining green sauce instructions that you can do while the meat is browning:
Add the remaining green sauce ingredients to a blender: 2 peeled onions, 3 de-stemmed jalapenos, 4 peeled garlic cloves, and 1/2 bunch of rinsed cilantro. I usually just twist off and discard the bottom, thicker portions of the cilantro but use the upper stems that hold the leaves together.
Once the poblanos have fully roasted, remove them from the oven and let them cool down for a few minutes. Pull off and discard as much of the skin as you can. De-stem and de-seed them. I find it easiest to cut off the tops and then make a slit lengthwise. Open up the pepper and use the knife to scrape out the veins and seeds.
Add the poblanos and tomatillos to the blender and combine well with the other ingredients. You might have to blend half first to get all of it to fit into a single blender.
Cut the pork shoulder into 1.5-2" chunks. I usually cut off any thick pieces of fat but I do try to leave some fat on each of the chunks. Season well with salt and pepper. Add a thin layer of oil to a Dutch oven or saucepot over medium-high heat. Once the oil is hot add the pork and try to create a single layer so that it browns evenly. You can do it in batches if you have to. Cook until well browned on both sides, approximately 3-4 minutes per side. Once browned, you can drain any fat if you want but I usually leave most of it in.
Add 1 cup of chicken stock to the pot along with 1/2 teaspoon salt, freshly cracked black pepper, 1 tablespoon Mexican oregano, and 1/4 teaspoon cumin (optional). It will simmer quickly and this gives you a chance to scrape up any bits of fond that are stuck to the pan.
Add the blended green sauce to the browned pork along with a final cup of stock. I usually add the final cup of stock to the blender and swish it around to get all the leftover green bits.
Bring the Chile Verde to boil and then reduce heat to a simmer, which was medium-low on my stove. Cover and simmer for 2-3 hours.
I usually test the pork after 2 hours. If it's tender and pulls apart easily then it's ready to serve. If it's tough then give it some more time on the stove. This batch simmered for about 2 1/2 hours.
Take a final taste for seasoning. I added generous pinches of salt and Mexican oregano at this point, but keep in mind this will depend on which stock you're using.
Serve over rice and optionally garnish with freshly chopped cilantro and a squeeze of lime. Be sure to serve plenty of the sauce in each bowl as that's the key to Chile Verde. Buen Provecho!
Store leftovers in an airtight container in the fridge.