Mix dry mustard, brown sugar, salt and tumeric together in a bowl. Sprinkle with vinegar to moisten. Continue moistening with flat beer. Mix together until mustard is a smooth thick creamy mixture. Put mustard in a jar that has a tight fitting lid. Chill in a refrigerator for future use. Source: British Columbia Heritage Cookbook : by Mary Evans-Atkinson pub 1984 : ISBN 0-920620-60-4 : Page 119