Sweet Hot Mustard In a small bowl, combine: 1/4 c dry mustard 2 Tb water Set aside minimum 10 minutes. (The longer this sits, the hotter the mustard will be.) In a 1 qt saucepan (double boiler works best), combine: 2/3 c water 1/3 c apple cider vinegar 1/4 c sugar 3 Tb all-purpose flour 1/2 t coarse sea salt Cook, whisking constantly over low heat until thickened ... about 3-5 minutes. Remove from heat and stir mustard base into the saucepan. Cover and refrigerate at least 24 hours. Keeps up to 4 weeks. Some web sites say keeps up to 1 year in glass jar and fridge. pdf attached