1) Combine the cucumbers, onions, pickling salt, and garlic in a large pot.
2) Add at least 2 inches of cracked ice to the top of the veggies.
3) Cover with a lid and refrigerate for 3-12 hours.
4) Drain and remove the remaining ice then remove the garlic and set aside.
5) In a large non-reactive sauce pan, combine the mustard, sugar, vinegar, celery seed and turmeric and bring this mixture to a boil stirring frequently.
6) Add the cucumbers and onions and bring the mixture back to a boil.
7) Bring the mixture to a simmer and continue cooking for a short time - approx. 5-10 minutes.
8) Pack your sterilized jars with the cucumber/onion mixture and then top off with some of the juice. Fill to within 1/2 inch of the rim.
9) Wipe the rims of each jar and put on lids snugly.
10) Place in a canning pot with at least an inch of water covering all of the jars and boil for 10 minutes.
11) Allow the pickles to cool on your counter top for a few hours. You should hear the pleasant 'pop' of the cans sealing. If you have a can that does not seal, just stick it in the fridge and eat that jar first.