Start by thoroughly washing the cucumbers and removing any dirt or debris. Cut off the ends of the cucumbers.

Prepare a brine by dissolving the pickling or kosher salt in four cups of filtered water. Stir until the salt is fully dissolved.

In a clean glass jar or fermentation vessel, add the garlic cloves, dill sprigs, black peppercorns, mustard seeds, and red pepper flakes (if using).

Pack the cucumbers tightly into the jar, making sure they are standing upright. Leave about an inch of headspace at the top.

Pour the brine over the cucumbers, covering them completely. Use a fermentation weight or a clean, food-safe object to keep the cucumbers submerged in the brine.

Cover the jar with a breathable lid or cloth to allow gasses to escape during fermentation.

Place the jar in a cool, dark place, away from direct sunlight. The ideal fermentation temperature is around 60 to 75 degrees Fahrenheit.

Let the cucumbers ferment for about three to seven days, depending on your desired level of sourness. Check the jar daily to release any built-up pressure by gently opening and closing the lid.

Taste the cucumbers periodically to monitor the flavor and texture. Once they reach your desired taste, transfer the jar to the refrigerator to slow down the fermentation process.

After a few days in the refrigerator, the pickles will be ready to enjoy. They can be stored in the refrigerator for several weeks.