Sprinkle the taco season and salsa over the top of the chicken.
Cover, and cook on low for 4-6 hours.
Take two forks and shred the chicken into bite-size pieces.
Fill the taco shells with the shredded chicken and top with the lettuce, tomatoes, cheese, and sour cream.
Notes
Chicken thighs: Chicken thighs tend not to dry out the way that chicken breast can. You can use an equal amount of chicken breast. If using chicken breast, start to check it around 3 hours.
Taco seasoning: You can make your own homemade taco seasoning or use a packet of taco seasoning. Feel free to use reduced-sodium, hot, or any other type of seasoning that you prefer.
Salsa: You can use any type of tomato-based salsa that you like.