Wash approximately 2 pounds of cucumbers under cold running water. Slice them thinly using a mandolin slicer and set aside.

In a bowl, add 3 teaspoons of salt and 3/4 cup of chopped onion to the sliced cucumbers. Toss to coat and cover with plastic wrap. Let sit for one hour.

In a medium pot, combine 1 cup of white vinegar, 1/2 cup of water, and 1 1/2 cups of sugar. Add mustard seed, celery seed, and bruised garlic. Heat over medium-high until boiling.

After one hour, drain the excess liquid from the cucumber mixture using a fine-mesh strainer and press down to remove more liquid.

Transfer cucumbers and onions back into the bowl. Pour hot brine over the mixture, making sure all pieces are submerged. Stir gently.

Pack the cucumber mixture tightly into sterilized jars, adding garlic pieces. Fill with remaining hot brine.

Let jars cool at room temperature for about 30 minutes. Seal tightly and refrigerate for at least 24 hours before tasting.