Yes, I believe starting and owning a restaurant would be considered entreprenurial, but it's not necessarily the right path for an MBA in my mind. Also, why are you going to back to business school now? Did the company fail?
Serving experience alone is not the right type of experience for an MBA. They want to see years of work, after college (not including internships) where you worked in an office environment of some sort. Waiting tables will not get you the experience or skills necessary for bschool, buuuut, you could make a case if you started your own restaurant or catering business etc... even this though would not be looked upon as highly as NY investment banking, private equity, venture capital, management consulting, or if you created a highly profitable company in the business sector.
Now if you started a chain of restaurants, or owned multiple locations with dozens of employees, then we have a whole different story.