The ability to attach dishes to specific users or roles is only possible if the option Share With All Users is disabled in the details tab of the dish, this setting is located here:
Click into the Admin Cogs
icon.Click into Menus, Dishes and Recipes.
Click into Manage Dishes.
Search and Edit the dish.
Locate Share With All Users on the Details tab and disable by unticking and clicking Save at the bottom of the page.
Once disabled there will now be additional tabs located at the top of the page named Users which will give you the ability to assign a user and or role to the dish:
Click into the Users tab.
Select the Site.
Select the User.
Click Attach to Dish to save the changes.