Combine ground vegetables and salt in a large glass mixing bowl, stirring well; cover and refrigerate 4 hours. Rinse in cold water, and drain.
Combine vegetables, vinegar, sugar, celery and mustard seeds, and red pepper in a large non-aluminum stockpot, stirring well; bring to a boil. Reduce heat; simmer, uncovered, 20 minutes or until vegetables are tender, stirring frequently.
Quickly ladle relish into hot sterilized jars, leaving 1/2-inch head space. Remove air bubbles. Cover with metal lids, and screw bands tight. Process in boiling water bath 10 minutes. Serve with meats or vegetables.