Put chicken, salsa, red pepper (if using), onion (if using), and taco seasoning in slow cooker. Stir to combine.
Cook on low for 6 hours.
Remove chicken, shred using two forks, and return to slow cooker. Add lime juice and cilantro, if using.
Serve over rice, tortillas, or chips with desired toppings.
You may use all dark or all white meat, whatever you prefer, as long as it's boneless.
Nutrition information is based on crockpot ingredients only, not garnishes or what you choose to serve it with.
If you want to REALLY simplify this, you can make it with just the chicken and the salsa, and omit all other ingredients.
If you want to make this more substantial, add 1 can (15-ounce) black beans, rinsed and drained and 1 can (15-ounce) corn kernels, drained, to the chicken after shredding. Cook for an additional 30 to 60 minutes or until heated through.