Butter Pickles

Wash your cucumbers thoroughly in cold water to remove any dirt. Slice off and discard $1/16$-inch of the blossom end of each cucumber (the blossom end contains enzymes that can soften pickles). Using a mandoline or sharp knife, slice the cucumbers into uniform $1/4$-inch thick rounds. Thinly slice the sweet onions.

In a large mixing bowl, toss the sliced cucumbers and onions with the $1/4$ cup of pickling salt. Cover the vegetables completely with 4 cups of crushed or cubed ice. Let stand at room temperature or in the fridge for 2 hours. The salt pulls excess moisture out of the cucumber tissue while the ice keeps the cell walls tight and firm.

After 2 hours, pour the cucumber and onion mixture into a large colander. Rinse thoroughly under cold tap water to remove excess surface salt. Drain completely and gently pat the slices dry with paper towels.

In a medium stainless steel saucepan, combine apple cider vinegar, white vinegar, granulated sugar, brown sugar, mustard seeds, celery seeds, turmeric, and allspice. Place over medium heat and bring to a gentle simmer, stirring frequently until all sugar crystals have completely dissolved. Turn off the heat.

Pack the drained cucumber and onion slices tightly into clean, glass pint or quart mason jars. Carefully ladle the hot brine over the vegetables, ensuring all slices are fully submerged while leaving about $1/2$-inch of headspace at the top of the jar. Tap the jars gently on a towel-lined counter to release trapped air bubbles.

Leave the jars open on the counter for about 45 to 60 minutes until they reach room temperature. Seal tightly with lids and transfer to the refrigerator. While you can eat them after 24 hours, flavor depth peaks around Day 3 or Day 4.