15) No one could turn around a failing restaurant as expertly as Gordon, whose experience and cadre of trained professionals was available at a moment's notice should his services be needed. This ability, some might call it a gift, was developed to such a level that other restaurant consultants were unable to match his results. This ability is best described as his:

core competency      

Explanation:

Core competency could be characterised as "a harmonised mixture of numerous assets and expertise that differentiate a business in the industry" and thus are the basis of the competition of the businesses.

A core competence is the culmination of a particular set of skills or manufacturing techniques that provide added value to the client. It can be very necessary for organisations to use and understand the concept of core competences.

They can use core competencies to excel in main product development. Organizations can also utilize core competencies to lift consumer and stakeholder expectations.        

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link :