In a small bowl, combine chili powder, ground cumin, smoked paprika, garlic powder, onion powder, dried oregano, salt, and black pepper. Mix well.
Heat olive oil in a large skillet over medium heat. Add chicken breasts and sprinkle the spice mixture evenly over both sides of the chicken.
Pour chicken broth into the skillet and bring to a simmer. Cover and cook for 20 minutes or until chicken is cooked through and tender.
Remove chicken from the skillet and shred it using two forks. Return shredded chicken to the skillet and stir to coat with remaining broth and spices. Cook uncovered for 3-5 minutes to reduce excess liquid.
Allow the shredded chicken to cool completely before portioning into freezer-safe containers or bags. Label and freeze for up to 3 months.
To serve, thaw chicken overnight in the refrigerator or reheat directly from frozen in a skillet over medium heat until warmed through.
Warm tortillas in a dry skillet or microwave for 20 seconds.
Assemble tacos by dividing shredded chicken evenly among tortillas. Top each with shredded cheddar cheese, lettuce, diced tomatoes, chopped cilantro, diced red onion, and a dollop of sour cream.
Serve immediately and enjoy your quick and flavorful freezer chicken tacos!