How can you sustain your restaurant with the growing restaurant trends? Is it just food or is it service? Or is it both?

Normally both but if you have the choice to choose just one thing i advice you to take " food" not service

Food is a back bone of any Restaurant and Service is a Head of the Restaurant Both Value Equally

best Food & good Service equal in maintaining restaurant customers

Its All about giving the best Food & Service with A must Of Maintaine it and make consistance 

Service and food equal in maintaining restaurant customers

Be consistent in your companies vision or the service principle that your company or restaurant stands for..product & services shouldn't be compromised since your repeated customers are coming for either both 

aspects ( your TLC  service and/or the taste of your food & drinks. In this way, you will alway have a share of customers from among your compset

pleasing  different paletts through mouth watering dishes and drawing a happy experience through a pleasant service will lead to  a memoriable experience  

if you trully implement and believe  on this you will maintain your restaurant comfortbly (if of course you respect the good financial forecost and the consitency of the othe business aspects,,,,,,)

To be sustainable in the business, it is necessary to ensure that the quality of food and service are maintained.