Tewkesbury mustard

Tewkesbury mustard is a blend of mustard flour and grated horseradish root. The mustard was developed in the English town of Tewkesbury in Gloucestershire, and gained a certain reputation in the 17th century, becoming a staple condiment of the kitchens of the time. Shakespeare mentions the mustard in Henry IV, Part 2, in which Falstaff has the line: “his wit's as thick as Tewkesbury Mustard” , describing the character of his friend Ned Poins. Originally the mustard was prepared by grinding the mustard seeds into mustard flour, combining this with finely-grated horseradish (and sometimes herbs and spices), then forming the mixture into balls which were then dried to aid preservation. The mustard balls would then be transported and sold in this form.

Source: Wikipedia