In a medium saucepan, combine the smashed garlic cloves, white distilled vinegar, water, white sugar, and kosher salt. Place the pan over medium-high heat and stir the mixture frequently as it heats to a boil, ensuring that both the sugar and salt fully dissolve.

Once the brine reaches a boil and the sugar and salt are dissolved, add the thinly sliced jalapeño peppers. Use a spoon to press them down so they're submerged in the brine. Remove the saucepan from the heat and let the jalapeños sit for 10 to 15 minutes, occasionally stirring and pressing them down to ensure even pickling.

Transfer the blanched jalapeños and garlic from Step 2 into 2 pint-size jars or 1 quart-size jar. Carefully ladle the warm brine from the saucepan over the peppers until the jars are full. Doing this over a small strainer helps remove most of the excess seeds. Allow the jars to cool completely at room temperature before securing the lids and refrigerating. I like to let the pickled jalapeños sit at least a day in the fridge for the best flavor.