Final answer:
In Squirrel, you can enter the customer's request for extra sauce on the side as a special instruction note in the order.
Step-by-step explanation:
In Squirrel, if a customer requests extra sauce on the side, you can enter it as a special instruction note in the order. When placing the order in the system, you can add a note specifying the customer's request for extra sauce on the side. This note will appear on the ticket and will be communicated to the kitchen staff.