Peel onions.
Wash cucumbers well and cut into slices about 1/4 inch thick. Separate
cauliflower into bite-size pieces. Cut red pepper into short strips.
Measure cold water into a large bowl. Add the salt and alum and stir
until salt is dissolved. Add vegetables. Let stand overnight. Drain very
well. Combine sugar, flour, mustard, turmeric and celery seed in a large
kettle. Stir until very well blended. Blend in vinegar gradually,
stirring until smooth. Set over moderate heat and cook until boiling,
thickened and smooth, stirring constantly. Add vegetables and heat over
moderate heat for 15 minutes, stirring occasionally. Ladle into hot
sterilized jars. Seal.
