Into a 2 or 3-quart slow cooker, add the salsa, cream of chicken condensed soup, and the taco seasoning. Give that a good stir until the sauce is smooth and creamy and all the ingredients are well incorporated.
Add the raw chicken right on top of the sauce. Flip the chicken over so both sides get covered in the delicious sauce.
Close the lid on the slow cooker and set it on Low for 4 to 6 hours or on High for 3 to 4 hours.
When the time is up, ensure that the chicken has reached an internal temperature of at least 165º Fahrenheit. If it hasn't, put the chicken back in the slow cooker and cook it for longer.
Once the chicken is fully cooked, remove only the chicken from the slow cooker and shred. With the shredded chicken still out of the slow cooker, mix in the sour cream until the sauce is nice and creamy.
Add the chicken back to the slow cooker, stir, and allow it to warm back up for about 5 to 10 minutes. Serve with your favorite toppings (see Notes below) or enjoy as-is!