Combine the onion, cucumber and salt in a large bowl. Toss well until the salt is nicely dispersed. Add 3 cups of ice cubes to the bowl, cover tightly, and refrigerate overnight. Drain the cucumbers, discarding the water, and set aside. Place the remaining ingredients in a large pot, stir to combine, and bring to a boil over medium-high heat. Add the cucumber and onion and stir well. Allow to return to a boil, then remove the pot from heat.

Transfer the pickles and the pickling liquid to a large clean glass or plastic container. Set aside to cool at room temperature, then cover and refrigerate overnight. The pickles will keep in the refrigerator for up to one week.