Heat a large skillet over medium-high heat. Season the chicken liberally with the cumin, smoked paprika, garlic powder, salt and pepper. Place the olive oil in the skillet and brown the chicken on both sides until golden brown.
Remove the chicken from the skillet (set it on a plate for now) and reduce the heat to medium-low. Add the onion and stir well, tossing to mix it in with any brown bits from the chicken. Cook for 5 minutes, until softened. Add in the garlic, fire roasted tomatoes, tomato paste, chipotle pepper and adobo sauce. Stir well. Cook until the mixture comes to a simmer, stirring often. Add the chicken back into the skillet. Cover and cook on medium-low until the chicken is cooked through, 15 to 20 minutes.
Remove the chicken (reserve the sauce, you’ll use it in a minute) and place it on a plate to shred it. Or! I use my kitchen stand mixer to shred it. Once shredded, mix it back in with the saucy contents of the skillet. Keep it warm and build your tacos! Chicken on the tortilla, then some pico, guac, queso fresco cheese and lots of lime.