Combine the cucumbers, onions, salt and any of the optional additional ingredients (we added 3 cloves sliced garlic).
Let stand 3 hours and then drain. Do not rinse.
In a large pot, mix the vinegar, mustard seed, turmeric, celery seed and sugar.
Add the vegetables and bring just to a boil.
Pack in hot, sterilised bottles.
Seal and store in a cool place for 1 month before using.
Without water bath processing, the pickles should last 6-9 months. You could water bath process the pickles to increase their shelf life but this will also make them less crisp.