Pat chicken drumsticks dry with a paper towel and place in a large, sealable plastic bag. Set aside.

In a medium glass or another non-reactive bowl, whisk the balsamic vinegar, olive oil, coconut aminos, chicken stock, red pepper flakes, and minced garlic together. Season with salt and pepper, if desired.

Pour one-half of the balsamic marinade over the chicken and seal the bag tightly. Turn the bag over until the chicken is coated. Place the bag in the refrigerator for a minimum of 30 minutes to overnight. Reserve the remaining marinade to use later.

When ready to prepare, preheat the oven to 400° and line a large rimmed baking sheet with parchment paper. Remove drumsticks from the plastic bag and arrange them on a lined baking sheet in a single layer without overcrowding. Discard the remaining marinade inside the bag.

- Place baking sheet in preheated oven for 30 minutes, then remove chicken from oven and turn each drumstick. After turning, brush the tops of each drumstick with the remaining marinade and return to the oven. Bake for another 20-25 minutes or until the chicken is well done and the outside has caramelized.

Remove from oven and let rest for 5 minutes. Transfer drumsticks to a serving dish and sprinkle with sliced green onions before serving.