Wash and sterilize 6 pint size jars, lids and screw caps, either in boiling water, hot soapy water or the dishwasher.  Do not re-use lids and screw caps.

In a large nonreactive stockpot, combine sliced cucumbers, onions, salt and garlic.  Cover with a flour sack towel and then cover with 2 - 3 inches of crushed ice.  Put a lid on and refrigerate for at least 4 hours, up to 12 hours.

Prepare a boiling- water canner or large pot of water, bring to a boil.

Remove towel and ice and transfer cucumber mixture to a colander and rinse well.  Discard garlic pieces.

In the same pot, combine sugar, apple cider vinegar, mustard seeds, turmeric and crushed red pepper.  Bring to a boil, stirring to dissolve sugar.  Stir in cucumber mixture from the colander and bring back to a boil.  Remove from heat.

Pack mixture of cucumbers and onions into sterilized jars with the liquid brine to about ½ inch from the rim.  Wipe jar rims, add lids and screw caps.

Process jars in boiling water bath for 10 minutes.  Remove jars to clean towel and let rest for 24 hours.  You'll hear lovely popping sounds as the jars seal.  If after 24 hours you have any jars that didn't seal, put in fridge and use in a couple of weeks.

This is the hard part, let the pickles rest for 4 - 5 weeks before opening.  Enjoy.