It was approaching 100 degrees in Hermosillo, the capital of Mexican border state Sonora, in mid-April, and it wasn’t even noon. Tucked in the sparse corridors of an open-air market called Tianguis Hector Espino, Armando Gil, an older gentleman with a white mustache and combed gray hair, sold root beer on draft from a mustard-hued stand.During my visit, Gil (pronounced “Hill”) didn’t hesitate to mention that his grandfather, chemical engineer Francisco Gil Ramîrez, is credited with bringing the soft drink to the city. There, he established Root Beer Gil in 1907 after working at a soda factory in Los Angeles, says great-grandson José Gil Salazar. In doing so, Francisco created a link between American and Mexican culinary cultures and kicked off the city’s root beer…