Chicken Drumsticks with Savory Glaze

Place rack in the middle of oven and preheat oven to 350 degrees. Cover a large baking pan with foil.
Arrange the drumsticks on the baking pan and sprinkle with salt and 1/2 teaspoon of the black pepper. Place the pan in the oven and bake for 40 minutes.
While the chicken is baking, bring water, garlic, lemon zest, sugar, vinegar, red pepper flakes, cumin and remaining black pepper to a boil in a small saucepan, Stirring occasionally until the liquid is reduced to 1/2 cup. Remove from the heat to cool.
When sauce has cooled, pour thru a sieve into a small bowl, pressing on solids to strain all liquid. Discard solids. Stir oyster sauce into cooled sauce. Transfer half of sauce into small bowl and set aside for serving.
After 40 minutes, begin brushing glaze onto the chicken. Place pan back in the oven for 5 minutes to allow glaze to caramelize. Repeat.
Use a meat thermometer on the thickest part of the drumstick to check that the chicken has reached an internal temperature of at least 165 degrees. If not, bake an additional 5 minutes and check again. Repeat as needed until 165 degrees has been reached.
Preheat the broiler on high. Brush a last layer of glaze on the chicken and place the pan under the broiler for a 1 - 2 minutes, until the chicken has char marks and the glaze is bubbling.
Remove from broiler and serve immediately with reserved sauce.