In the heart of Delaware, Ohio sits a time capsule disguised as a diner, where milkshakes are whipped to such perfection that locals have been known to drive miles out of their way just for a sip.

For non-beer drinkers, their Oinksterade (house-made lemonade with a hint of orange zest) provides a refreshing counterpoint to the richness of the food and shakes. The Oinkster has become something ...