Combine the soy sauce, Thai sweet chili sauce, fish sauce and ginger root in a large resealable container. Add the drumsticks and toss to coat. Place in the fridge and allow the chicken to marinate for at least 3 hours, up to overnight.
When ready to cook the chicken, dump the chicken and the marinade into a 6-quart slow cooker. Cook on low for 5 to 6 hours, or on high for 3 hours.
Turn on the broiler. Cover a baking sheet with foil and carefully transfer the chicken to the baking sheet. Brush with some of the remaining marinade and broil on high for 3 minutes on each side, flipping once and brushing with more sauce.
Remove from the oven and garnish with cilantro and sesame seeds, if desired.
