With regards to tickets in a restaurant, an “add on” is a ticket with additional appetizers or entrées that did not come in with the original ticket. The most common case for this when a table puts in an order for appetizers and then the waiter returns later for entrée selections. In a more difficult situation, it can mean that a diner requests an additional entrée item at the time that appetizers are being cleared from the table. In such cases, the expediting chef will typically have to ask for a line-cook to add on that item on the fly eg. “Adding on to that last fire one chicken mila”. If the item is time consuming it could result in the entire table going to “hold fire” before the other item is ready to be picked up with the other items for the table.
Kitchens generally don’t like add-ons as a common practice during a busy service and will instruct waiters to get the entire order together before submitting it to the kitchen. The reason being is that entrées typically take a long time to prepare and if a table is receiving their appetizers when they order their entrees, there likely is not enough time to prepare the main courses before they need to be fired in 5 to 10 minute intervals with other tables.
Expediting chef reading the ticket machine as table 32’s appetizers are hitting the pass: “Table 32 adding on… Order in one bass, one char, two chicken same table”