from https://ofbaking.wordpress.com/2011/08/28/bread-and-butter-pickles/

ingredients

• 5 lb cucumbers, ends removed, sliced into 1/4″ coins
• 1 lb large onions, roughly chopped
• 1/2 cup plus 1 tbsp kosher salt (just make sure not to use salt with added iodine)
• 2 cups ice cubes
• 4 cups white, distilled vinegar (if you plan on canning, never reduce the amount of vinegar or use a different kind of vinegar than called for in a recipe as the acid in vinegar helps keep your canned food shelf-stable)
• 2 cups water (again, if canning, use distilled or un-chlorinated water–Chicago’s tap water uses chlorine to sterilize, but this will mess up your cheese and pickle making)
• 1 cup sugar
• 2 tbsp mustard seed
• 1 tbsp black peppercorns
• 1 tbsp celery seed
• 1 tbsp turmeric

directions

1. Layer the cukes and onions with 1/2 cup of salt in a (very) large bowl and cover with a layer of ice cubes.  Set aside for 2 hours. Drain and rinse in a colander.
2. Combine the vinegar, water, sugar, mustard seed, peppercorns, celery seed, tumeric, and the remaining 1 tbsp salt in a large, nonreactive saucepan (no aluminum!) and bring to a boil.  Add the drained vegetables and return to a boil, stirring to ensure that all of the vegetables are heated through.  Remove from heat.
3. Refrigerate: ladle into bowls or jars.  Cool, cover, and refrigerate for up to 3 weeks.