*Preferably Colmans. **Or more to taste of either the fresh or dried tarragon. If using a spice mill, grind the mustard seed in it to the texture of coarse meal. Stir the ground seed with the mustard powder and water and set it aside, uncovered, for at least 2 hours or as long as overnight, giving it a stir when you think of it. If using a blender or food processor to do the grinding, combine the seed, mustard powder and water in the container; process everything to a coarse puree. Set the mixture aside as described. Combine the mustard mixture with the vinegar, honey, salt and tarragon. Process the mixture in a blender or food processor to the texture that suits you, from slightly coarse to creamy. Store in a clean, dry jar, tightly capped, at room temperature if you would like it to mellow gradually, or refrigerate it at once to retain maximum hotness. It can be used at once, but a few days rest in the jar will allow the flavor to develop. After the mustard has rested for a day or two, taste it and decide whether to add more tarragon, honey or vinegar. Good with summer picnic foods. Yield: About 2 cups. Keeps indefinitely, either at room temperature or in the refrigerator. From _Fancy Pantry_ by Helen Witty. New York: Workman Publishing Company, Inc., 1986. Pp. 183-184. ISBN 0-89480-037-X.