Place the chicken breasts in the bottom of the crock pot.
Sprinkle the taco seasoning evenly over the chicken.
Pour in the chicken broth and diced tomatoes.
Add the chopped onion and bell pepper on top.
Cover and cook on low for 6-8 hours or high for 3-4 hours.
Once cooked, shred the chicken using two forks.
Stir the shredded chicken into the juices for added flavor.
Warm the tortillas in a skillet or microwave.
Assemble the tacos by adding the chicken mixture to the tortillas.
Top with your favorite toppings and serve immediately.