From TNG
Percheron Freres mustard is made from a variety of seed called Brassica Juncea better known as “brown seeds” and from another variety called Sinapis Alba also known as “white seeds”. Its characteristic is to delivery a very spicy note when it’s being ground. To product Percheron mustards, the seed is mixed with a “verjuice” (water, salt, vinegar) whose composition can change according to the recipe. The use of different vinegars, wines, spices, herbs or fruits makes it possible to create a wide range of mustards, with different flavours. The mustard is now an integral component in the kitchen.