Final answer:
The corrective action was reheating the soup to 165°F for 15 seconds, which is above the safe temperature threshold to prevent bacterial growth.
Step-by-step explanation:
The corrective action taken by the chef was reheating the minestrone soup to 165°F for 15 seconds. When foods are not held at their proper temperatures, the risk for microbial growth increases, which can lead to foodborne illness. Foods need to be kept hot at 135°F or above to prevent bacterial growth. If the temperature falls below this critical limit, as it did in this case (120°F), the proper corrective action is to reheat the food to a safe temperature. The U.S. Department of Agriculture (USDA) recommends reheating soups to a rolling boil to ensure safety, which correlates with the chef's action to reheat the soup well above the boiling point to a temperature capable of killing harmful bacteria.