01 - Whisk together the soy sauce, honey, hoisin sauce, rice vinegar, brown sugar, sesame oil, minced garlic, grated ginger, and red pepper flakes in a medium bowl until thoroughly combined.
02 - Arrange chicken drumsticks in the slow cooker. Pour the prepared glaze over the chicken, turning each piece to ensure even coating.
03 - Cover and cook on low setting for 4 hours until chicken is thoroughly cooked and tender, reaching an internal temperature of 165°F.
04 - Transfer drumsticks to a serving platter and cover loosely with aluminum foil to retain heat.
05 - Pour the cooking liquid into a small saucepan. Combine cornstarch and water in a separate bowl to create a slurry, then stir into the saucepan. Bring to a boil over medium-high heat, stirring constantly for 2-3 minutes until sauce thickens.
06 - Brush or spoon the thickened glaze generously over the drumsticks. Garnish with thinly sliced scallions and sesame seeds immediately before serving.