I was talking to my wife today and we were trying to come up with restaurants that changed the OKC food scene. Not sure how far you want to go back, but I moved here in 1999 and my list would be:

Cheevers (emergence of the Paul’s and their restaurant group)
Big truck tacos (I know, I know, random, but before them, there were Southside taco trucks and fast food)
The mule (first restaurant in the plaza district that established the district)

I could list about 25 off the top of my head, but thought this might be a good start and wanted to get other peoples opinions.