Grey Poupon Wholegrain French Mustard. The secret ingredient of Grey Poupon mustard is the white wine which makes all the difference to the flavour of our mustard! Authentic French Mustard made in Dijon using a traditional and authentic recipe since 1777. Wonderfully versatile: Grey Poupon is the only Wholegrain Mustard worth cooking with. Add a spoonful of flavour to your cooking or a dollop to your side of plate! Delicious French Mustard with white wine: Grey Poupon is the authentic French Dijon and Wholegrain mustard made in Dijon.