Tuckers onion burgers for food. It's a local, fast casual with 5-6 locations around OKC and Norman. My wife is from OKC and when we go back to visit her parents, I stop there immediately.
They also have a fast food chain that is local to Oklahoma called Braum"s. It's the In and Out Burgers of Oklahoma. Incredible burgers and the best shakes made with fresh ingredients daily.
Just got my Tennessee/ Oklahoma tickets yesterday !!