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 completely smooth and combined.
02 - Arrange the chicken drumsticks in the slow cooker. Pour the prepared glaze over the chicken, turning each piece to ensure even coating on all sides.
03 - Cover and cook on low setting for 4 hours or until the chicken registers 165°F internally and the meat is tender enough to pull easily from the bone.
04 - Transfer the drumsticks to a serving platter using tongs and cover loosely with aluminum foil to retain heat while preparing the sauce.
05 - Pour the cooking liquid from the slow cooker into a small saucepan. Mix the cornstarch and water in a separate small bowl until smooth to create a slurry.
06 - Stir the cornstarch slurry into the saucepan with the cooking liquid. Bring to a boil over medium-high heat, stirring constantly for 2-3 minutes until the sauce thickens and coats the back of a spoon.
07 - Brush or spoon the thickened glaze generously over the drumsticks. Sprinkle with sliced scallions and sesame seeds immediately before serving.