This data is cached across all restaurants for a given partner, so all menus across all restaurants that appear when you query your list of restaurants from the Restaurants endpoint will be returned to you. You can identify which menus belong to which restaurants by looking at the restaurant_id key in a given menu object.
We recommend you organize the menus into buckets based on the restaurant_id that they're related to. Due to the size of the data, this larger format keeps this endpoint loading quickly in this first release.
You'll combine this menu data with the list of menus that appear at a specific Ordering Page to create the given menu screen that patrons will see, then poll the Fulfillable Menu Items endpoint to see if the menu items are all still able to be ordered from that menu.