Wash and scrub the Lebanese cucumbers. Trim the ends and cut them into lengthwise quarters.

In a large stainless steel pot, combine the vinegar, water, sugar, and black peppercorns. Bring to a boil, then reduce the heat and let it simmer for 15 minutes.

Meanwhile, sterilize the empty jars in boiling water for 5 minutes.

Place a sprig of dill at the bottom of each hot jar, followed by distributing the mustard seeds.

Pack the cucumber quarters and garlic cloves into the hot jars, leaving a 2 cm (3/4 inch) space at the top.

Pour the hot brine over the cucumbers, leaving a 1 cm (1/2 inch) space at the top and ensuring the cucumbers are completely submerged.

Insert a non-metal utensil into the jars and stir to release any air bubbles. Add more brine if necessary.

Process in a boiling water bath for 15 minutes.