Here is a quick guide on your case.
Key components to achieving this scenario or system.
A. Use a Claim form where user can submit their details to claim the Free Appetizer.
B. User Toast APIs to Post a New order when a claim form is submitted.
The scenario should work like this;
Module-1 Get forms submission (either instant or at a scheduled interval)
Module-2 Use the HTTP module to work with Toast API and create a new order and map the inputs from form details.
Module-3 Update the user status to Go High-Level database that the user claimed the free gift and use that for further marketing.
This way the person who claims will be tracked and his status will be updated in GHL.
I hope this help.
Refer the Toast Post Order API here: Post an order