Pour the water into a medium-sized sauce pan and warm over medium-low heat until it reaches about 100 F. Sprinkle in the salt, and whisk it into the hot water until it dissolves. Pour the warm saltwater into a pitcher, and let it cool to room temperature.
Pack a quart-sized fermentation jar with whole pepperoncini, taking care not bruise them. Place the garlic cloves and bay leaf among the peperoncini, and pour in the cooled saltwater brine. Seal the crock, and allow the peppers to ferment for 10 days. Their color will fade and yellow. After about 10 days, open the crock and try a pepper. If you prefer a sourer flavor, continue fermenting the peppers until they acquire the flavor you like, testing every 5 to 7 days, at your leisure. Transfer to the refrigerator or cold storage. Brine-pickled peperoncini will last about 1 year, properly fermented.