Place chicken in a 3- or 4-qt. slow cooker. Top with onion, garlic and ginger. Combine broth, soy sauce, honey, pepper flakes and pepper; pour over chicken. Cook, covered, on low until chicken is no longer pink, 3-1/2 - 4 hours., In a small bowl, mix cornstarch and water until smooth; gradually stir into slow cooker. Cook, covered, on high until sauce is thickened, 15-30 minutes. When chicken is cool enough to handle, shred chicken with 2 forks; return to slow cooker. Serve with rice, if desired. Garnish with cilantro and sesame seeds.