The key to searing chicken in a skillet is ensuring the oil in the pan is at a hot enough temperature to trigger the Maillard Reaction. In my smoked short ribs recipe, I go into how the reaction occurs between amino acids and sugars and how that helps provide amazing flavor. It can only be attained with the right temperature, a certain acidity level, and proper moisture content. The heat level, olive oil, natural sugars from the onions, and acidity level left over from the garlic helps trigger this Maillard Reaction when the meat is added to the skillet.