You could try asking the chef. However, some restaurants might not like giving away their "secrets." Also, if they make their recipes in bulk (in large quantities), they wouldn't be able to give you the recipe in amounts that can be used for just 4-8 people.
There are books that duplicate restaurant recipes, such as:
Rosso Restuarant
Restuarant
A Thai and Eatery cafe
People
un restaurant
u can eat in a restuarant in greece
either in a restuarant or at a clambake!
'Restuarant italienne'
TGI fridays
what is nick's favorite restuarant
you could go to a restuarant or buy a generator
They have many kinds of restaurants in Zambia.