At the intersection of Route 66 and the Chisholm Trail lies the historic town of El Reno, host to the annual Fried Onion Burger Day Festival, during which the world’s largest onion burger is created, all 750 pounds of it. A much more manageable rendition of this local specialty, however, can be found at Johnnie’s Grill. This roadside restaurant has been serving these caramelized onion-laden burgers since opening in 1946, and they are titanic in taste. On a daily basis, the diner specializes in such hearty fare as chili and Fritos pie, the Arkansas sandwich (two eggs between pancakes), and a sublimely sloppy Coney dog topped with chili and sweet coleslaw. The pies and cakes are heavenly. No alcohol available. Serving breakfast, lunch and dinner daily.