Pat the chicken dry with paper towels and season with salt and pepper.
Heat 1 tablespoon oil in a Dutch Oven over medium to medium-high heat until shimmering. Cook half the chicken thighs until brown on both sides, about 4-5 minutes per side.
Remove the chicken to a large plate and continue cooking the remaining thighs. Reduce the heat to medium and add 1 tablespoon vegetable oil. Heat until shimmering and then add the onion. Cook until the onions start to brown, about 5 minutes. Add the garlic, cumin, oregano and the powdered chipotle chili pepper (if using) and cook for 1 minute or until fragrant. Add the can of fire roasted tomatoes, chicken broth, chipotle peppers, adobo sauce, and 1 teaspoon brown sugar. Bring to a boil, scraping the bottom of the Dutch oven to loosen any brown bits.
Add the browned chicken to the pot, and reduce the heat to medium-low. Cover the Dutch oven and simmer for 10 minutes. Turn the chicken, cover and cook for another 20 minutes.
Remove the chicken thighs from the sauce and set aside to cool slightly. Using an immersion blender, process the tomato sauce in the Dutch oven until smooth. (Carefully tilt the Dutch oven to one side to make it easier to process) If you don’t have an immersion blender, you can use a regular blender or food processor. Take care when pouring hot liquids into the blender carafe.
Shred the chicken using two forks into bite size pieces and return to the sauce in the Dutch oven. Heat over medium-low, uncovered and stirring frequently, until the sauce is thickened and the chicken is coated, about 10 minutes. Add the lime juice, salt and pepper. Stir until blended. Serve and enjoy!