Wash the cucumbers thoroughly and slice them into thin rounds or spears, depending on your preference.

In a medium saucepan, combine the vinegar, water, sugar, and salt. Heat over medium heat until the sugar and salt dissolve, stirring occasionally. Remove from heat and let the brine cool slightly.

Place the garlic cloves, mustard seeds, dill seeds (or fresh dill), and red pepper flakes (if using) into a clean glass jar or container.

Pack the sliced cucumbers tightly into the jar, leaving about 1/2 inch of space at the top.

Pour the cooled brine over the cucumbers, ensuring they are completely submerged. Seal the jar tightly with a lid.

Place the jar in the refrigerator and let the pickles sit for at least 24 hours before serving to allow the flavors to develop. For best results, wait 48 hours.