The endothermic gas reaction takes place in two steps or stages. In the first stage, some of the methane. burns with air creating an exothermic (heat generating) reaction. In the second stage, the surplus methane. reacts with the carbon dioxide and water vapor produced in the first stage. This second stage is endothermic. (heat absorbing).
Pat the chicken drumsticks dry with clean paper towels. Cover them with plastic wrap or aluminum foil to warm them up to room temperature for 30 minutes. Preheat a gas or charcoal grill to 400 degrees F. If you are using a charcoal grill without a temperature gauge, this will take about 20 minutes.
1 Heat grill. 2  Spray grill (or onions!) with non-stick cooking spray, or brush with olive oil. 3  Lay onion rounds on the grill, close it, and grill for 10-15 minutes. 4  Check at the halfway point, and turn rings over with a spatula if you want to fiddle with them. 5  Or donât, if you donât.