Rinse the chili peppers thoroughly under running water, ensuring any dirt or debris is removed. If handling whole chilies, wear gloves to protect your skin from their potent heat. If slicing, carefully cut them into rings before packing them into sterilized glass jars.

Divide the garlic cloves evenly between the jars, adding two cloves to each. If using a single large jar, place all the garlic cloves in that jar. Pack the peppers as tightly as possible, ensuring minimal empty space.

In a medium saucepan over medium heat, combine the filtered water, distilled white vinegar, and kosher salt. Stir gently and bring the mixture to a gentle simmer, allowing the salt to dissolve completely. Be careful not to let the liquid reach a full boil.

Once the brine is ready, remove it from the heat. Using a ladle, carefully pour the hot liquid over the peppers, ensuring they are fully submerged. Allow the jars to cool at room temperature for about an hour before sealing them with tight-fitting lids.

Transfer the jars to the refrigerator and let the peppers marinate for at least 24 to 48 hours before enjoying. These pickled Thai chili peppers add a fiery kick to any dish and continue to develop their bold flavor over time.