Roast the poblano pepper, blistering the skin over flame or on broil in the oven until it starts to blacken all over
Remove poblano and wrap in plastic wrap to sweat. After approx. 15 minutes the skin will release, easily peeling off leaving you with roasted pepper. When cool, cut into slices
Heat a large pot to medium-high heat and add the oil.
Add chicken and season with half of your salt and pepper.
Cook, turning until browned on all sides Approx. 5 minutes. Transfer to bowl or plate.
Add poblano, bell pepper, and onion, season with remaining salt and pepper. Cook until tender and starting to carmelize, 5 to 7 minutes.
Add garlic and taco seasoning and sautee for approx. 1 minute until fragrant.
Add broth and deglaze pot, scraping any bits stuck to the bottom of your pot.
Add chicken back to pot as well as any collected juices.
Bring to a boil then reduce to a simmer and continue to cook uncovered until chicken is cooked through. Approx. 15-30 minutes depending on how the chicken was cut.
Remove chicken from pot and chop or shred and return to pot.
Season with additional salt and pepper to taste and serve.