Heat olive oil in a large skillet or pot over medium heat. Add the chopped onion and cook until softened and translucent, about 5 minutes.

Add the minced garlic, chipotle peppers, adobo sauce, cumin, oregano, and chili powder to the skillet. Stir well to combine and cook for an additional 1-2 minutes to release the flavors.

Pour in the fire-roasted diced tomatoes, including the juices. Stir everything together and bring the mixture to a simmer.

Blend sauce well until smooth, return to pan.

Add the shredded chicken to the skillet and mix well to coat the chicken with the sauce. Season with salt and pepper to taste.

Reduce the heat to low and let the chicken tinga simmer for 15-20 minutes to allow the flavors to meld together. If the mixture becomes too thick, you can add a splash of water or chicken broth to adjust the consistency.

Serve the chicken tinga warm with your choice of accompaniments, such as warm tortillas, rice, beans, guacamole, salsa, or any other toppings of your liking.