Preheat your oven to 400°F (200°C).
In a small mixing bowl, whisk together soy sauce, water, sesame oil, apple cider vinegar, Erythritol, minced garlic, and minced ginger to create the teriyaki sauce.
Place the chicken drumsticks in a large zip-lock bag or shallow dish. Pour half of the teriyaki sauce over the drumsticks, ensuring they are well-coated. Marinate in the refrigerator for at least 30 minutes.
Line a baking sheet with baking paper. Place a wire rack on top.
Arrange the marinated chicken drumsticks on the wire rack, leaving space between each.
Bake in the preheated oven for about 35-40 minutes or until the internal temperature reaches 165°F (75°C) and the skin is crispy.
While the chicken is baking, pour the remaining teriyaki sauce into a small saucepan. Simmer on low heat until it thickens to the desired consistency.
Once the chicken is done, brush it with the thickened teriyaki sauce. Sprinkle with sesame seeds.
Serve the keto teriyaki chicken drumsticks hot, garnished with chopped green onions and a green salad or keto-friendly noodles on the side.