Preheat the oven broiler to high. Line a rimmed baking sheet with aluminum foil for easy clean up.
Scatter the tomatillos, peppers, and onion on a baking sheet. Drizzle with 1 tablespoon of oil and sprinkle with about ½ teaspoon each of salt and pepper, or to taste.
Place a rack about 6 inches from the broiler. Broil the vegetables until there is some slight charring, approximately 5 to 7 minutes. Stir and place back under the broiler for another 5 to 7 minutes.
Pull the pan out of the oven and set aside.
In a Dutch oven over medium-high heat, add the remaining tablespoon of oil. Once hot, lightly brown the chicken thighs on both sides. Do this in batches as necessary.
Add the garlic and cook, stirring constantly for about 30 seconds.
Add the cumin, oregano, stock, fish sauce, and roasted veggies plus any juices they released. Stir to combine.
Submerge the chicken thighs under the stock/vegetables. Place the lid on the Dutch oven slightly ajar and simmer for about 15 to 20 minutes or until the thighs are cooked through, reading 165 degrees F on a digital thermometer.
Remove the thighs from the pot and place them in a bowl or on a baking sheet. The baking sheet used to roast the vegetables is fine. Allow the chicken to cool enough to be able to handle. Shred or chop the chicken and place it back into the pot.
Pour the beans, cilantro, and lime juice into the pot and stir gently. Taste for seasonings, adjusting as desired.
Serve hot in bowls with toppings of your choice.