01 -
Combine tomato sauce, granulated sugar, light brown sugar, low-sodium soy sauce, white vinegar, and mustard in a large pot over medium-high heat. Stir thoroughly until well blended, then bring to a gentle boil.
02 -
Add chicken drumsticks to the sauce. Reduce heat to medium-low, cover, and simmer for 20 to 30 minutes, or until the chicken is just cooked through. Remove the drumsticks to a plate and reserve a portion of the sauce in a cup.
03 -
Preheat the grill to high heat. Clean and oil the grates thoroughly. Once hot, place the drumsticks on the grill, basting with reserved BBQ sauce. Rotate continuously until the skin is caramelized and lightly charred, about 2 to 4 minutes per side.
04 -
Transfer to a serving platter and accompany with preferred side dishes.