Dice the vegetables and layer them in a bowl with the pickling salt. Refrigerator overnight to remove moisture from the vegetables.
Rinse and drain the vegetables.
To make the marinade, in a large noncorrosive stockpot mix sugar, vinegar, tumeric, ginger, dried mustard, mustard seed, celery seed, and pickling spice sachet. Bring to a boil, and boil for 2 minutes.
Add the vegetables to the pot and boil for an additional 10 minutes.
Remove the pickling spice sachet and add the pickled onions (if using them) and boil for another 2 minutes.
Remove from stove and allow to cool.
Pack the vegetables in jars, then fill with the pickling mixture until the vegetables are covered. Store and refrigerate in covered jars. Serve chilled as a relish or on sandwhiches.