Place the chicken thighs, half of the red onions, sliced carrots, lemon juice, dried oregano, dried basil, dried thyme, minced garlic and chicken broth in a crock pot.
Cover crock pot with lid and cook on low for 6 hours or on high for 3 hours until the chicken is easily shreddable.
Shred the chicken and stir it into the ingredients in the crock pot.
For the Tzatziki:
Peel and deseed the cucumber.
Shred the cucumber into small pieces.
Stir the cucumber in a small bowl with the remaining tzatziki ingredients until well combined.
For Serving:
Serve the chicken mixture on pitas topped with the tzatziki sauce and enjoy!