Horseradish
Horseradish sauce made from grated horseradish root and vinegar is a popular condiment. In the United Kingdom it is usually served with roast beef, often as part of a traditional Sunday roast. It can also be used in a number of other dishes, including sandwiches or salads. A variation of horseradish sauce, which in some cases may substitute the vinegar with other products like lemon juice or citric acid, is known in Germany as Tafelmeerrettich. Also popular in the UK is Tewkesbury mustard, a blend of mustard and grated horseradish originating in medieval times and mentioned by Shakespeare (Falstaff says: "his wit's as thick as Tewkesbury Mustard" in Henry IV Part II). A very similar mustard, called Krensenf or Meerrettichsenf, is popular in Austria and parts of Eastern Germany.