What kind of mustard do they use at Fenway Park?

What kind of mustard do they use at Fenway Park? Eventually, the new Fenway Frank was approved, sporting a slightly bolder flavor thanks to Kayem’s special concoction of spices and meats. The fabulous Fenway Frank, complete with a healthy squirt of yellow mustard.

Eventually, the new Fenway Frank was approved, sporting a slightly bolder flavor thanks to Kayem’s special concoction of spices and meats. The fabulous Fenway Frank, complete with a healthy squirt of yellow mustard.