In a large skillet, heat the olive oil over medium heat. Add the chopped onion and sauté until translucent, about 5 minutes. Add the minced garlic and cook for an additional minute until fragrant.

In a small bowl, mix together the chili powder, cumin, smoked paprika, oregano, salt, and black pepper. Sprinkle the spice mixture over the onions and garlic, stirring to combine.

Add the chicken breasts to the skillet, followed by the chicken broth and diced tomatoes with green chilies. Bring the mixture to a simmer.

Cover the skillet and reduce the heat to low. Cook for 25-30 minutes, or until the chicken is cooked through and easily shreds with a fork.

Remove the chicken from the skillet and shred it using two forks. Return the shredded chicken to the skillet, stirring to combine with the sauce.

Warm the tortillas in a dry skillet or microwave.

To assemble the tacos, place a portion of the pulled chicken on each tortilla, then top with shredded lettuce, diced tomatoes, cheese, and cilantro. Serve with lime wedges on the side.