Place in a heatproof glass bowl:
      About 2 ounces dry mustard
Pour over the mustard to cover it:
      Water at a rolling boil
Set the bowl over, not in, rapidly boiling water. Stir the mustard into a paste but make sure that there is enough liquid to cover the mustard. Drain off any excess water. Cover and cook for 15 minutes. If desired, add:
      1 teaspoon sugar (optional)
      1/4 to 1/2 teaspoon salt (optional)
For a brightly colored mustard, add
      1/4 teaspoon ground turmeric (optional)
Place in a jar and let cool, uncovered, for 1 to 2 hours. Cap tightly. Keep this mustard at room temperature, not refrigerated, for up to 2 weeks.