I finally tried A.G. Barr’s Irn-Bru during a trip this month to Scotland. The carbonated soft drink is said to outsell even Coca-Cola and PepsiCo in the country. Irn-Bru is dubbed “Scotland’s other national drink,” coming after, of course, Scotch whisky. The soda has its own closely guarded “secret recipe.” At Edinburgh airport, an Irn-Bru branded orange and blue vending machine awaited my arrival — it also contained Coke, Diet Coke, and 7Up.

Irn-Bru’s flavor is hard to describe. I’ll try. While the drink has a medicinal orange color, it doesn’t taste anything like the orangy flavor of a Fanta or a Crush. There are bitter tonic notes owing to the quinine in the formula. Perhaps Irn-Bru would work well as a mixer for gin? I’m not sure of that. Apparently, young Scots...