Recipe for French Mustard
Slice 1 large onion into 1 cupful of vinegar and leave a day or two. Pour off the vinegar and add to it: 1 teaspoonful pepper. 1 teaspoonful salt. 1 tablespoonful sugar. Thicken with mustard flour to the proper consistency, first rubbing the mustard smooth in a little vinegar. A little salad oil is considered an improvement by many. Bottle, cork closely and wait a week before using.