In a large pot or Dutch oven, heat the vegetable oil over medium heat.
Add the chicken pieces and cook until browned on all sides. Remove the chicken and set aside.
In the same pot, add the chopped onion, minced garlic, and green bell pepper. Sauté until the onion is soft and translucent, about 5 minutes.
Stir in the chopped tomatillos, cilantro, and parsley. Cook for another 5 minutes until the tomatillos start to break down.
Stir in the ground cumin, dried oregano, black pepper, and cayenne pepper (if using). Cook for 1-2 minutes to toast the spices.
Pour in the chicken broth and bring to a boil.
Return the browned chicken pieces to the pot. Reduce the heat to low, cover, and simmer for about 45 minutes to 1 hour, or until the chicken is tender and cooked through.
Remove the chicken from the pot and shred it using two forks. Return the shredded chicken to the pot.
Adjust seasoning with salt to taste.
Enjoy your meal!