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 fully incorporated and smooth.
02 - Arrange the chicken drumsticks in the slow cooker insert. Pour the prepared glaze over the chicken, turning each piece to ensure even coating on all sides.
03 - Cover the slow cooker with the lid. Cook on low heat setting for 4 hours or until the chicken reaches an internal temperature of 165°F and the meat is tender and beginning to pull away from the bone.
04 - Transfer the cooked drumsticks to a serving platter using tongs. Cover loosely with aluminum foil to keep warm while preparing the sauce.
05 - Pour the cooking liquid from the slow cooker into a small saucepan. In a separate small bowl, combine the cornstarch and water, stirring until smooth to create a slurry. Whisk the slurry into the saucepan with the cooking liquid.
06 - Place the saucepan over medium-high heat and bring to a boil while stirring constantly. Continue cooking 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 just before serving.