Place the chicken thighs in the CrockPot. In a separate bowl, whisk together the orange juice, soy sauce, honey, rice vinegar, garlic, ginger, sesame oil, and red pepper flakes. Pour this mixture over the chicken in the CrockPot.
Cover and cook on low for 6-7 hours or on high for 3-4 hours, until the chicken is cooked through and tender.
Once cooked, remove the chicken from the CrockPot and shred it using two forks.
In a small bowl, mix the cornstarch and water to create a slurry. Stir this slurry into the sauce in the CrockPot. Turn the heat to high and let it cook for an additional 15-20 minutes, or until the sauce thickens.
Return the shredded chicken to the CrockPot and stir to coat it in the thickened sauce.
Serve the orange chicken over rice or noodles, garnished with sliced green onions and sesame seeds.