Start by microwaving onions and garlic in a small microwave-safe bowl for about one to two minutes until the onions turn soft and translucent.
Stir in ketchup, vinegar, lemon juice, chili, brown sugar, honey, Worcestershire, mustard, paprika, molasses, pepper flakes, and celery seeds until well combined.
Divide the barbecue sauce in half, reserving one portion for basting and the other for serving.
Wash and pat the drumsticks dry with paper towels.
On a cutting board, use a sharp knife or kitchen shears to cut through the tendons around the bottom end of each drumstick.
Push the meat toward the top, then bend and pull out the joint, using kitchen shears if needed.
Scrape off any remaining skin on the bone.
Trim a small part of the cartilage from the meaty side to help the drumstick stand upright.
Place the prepared chicken in a large bowl, add oil, Creole seasoning, and salt, and toss until well coated.
Let it marinate in the fridge for at least 30 minutes and up to two hours.
Preheat the oven to 350℉ (177℃).
Arrange the chicken meat-side down on a wire rack set over a foil-lined baking tray.
Bake for 20 minutes until the skin crisps and fat renders.
Remove from the oven and generously baste with one portion of the barbecue sauce.
Return to the oven and bake for another 10 minutes, rotating the tray midway for even browning.
Ensure the internal temperature reaches at least 165℉ (75℃).
Take the chicken out and serve with the remaining barbecue sauce.