Wash the Persian cucumbers and place them on a cutting board. Use a sharp knife to slice the cucumbers into halves or spears. There's no need to cut the ends of the cucumbers off unless there is a long stem poking out.

Divide the sliced cucumbers between two 1-quart mason jars. Similarly, divide the chopped garlic, mustard seed (or coriander seeds), red pepper flakes, and fresh dill sprigs between the two jars.

Combine vinegar, water, and sea salt in a small saucepan and heat over high heat until it comes to a full boil. Remove the pickling liquid from the heat and allow it to cool for a few minutes.

Pour the hot brine into the two large jars, filling them all the way up. Seal the jars using the airtight lids and allow the jars of pickles to cool to room temperature before refrigerating them.

Pickle spears will taste best 4 to 5 days into the pickling process, but you can start eating them on day 2 if you’d like. For thin cucumber slices, the pickles will be ready after 24 hours.