Prepare the Cucumbers: Wash the cucumbers thoroughly and cut them into spears or rounds, as desired.
Sterilize Jars: Sterilize glass jars and lids by boiling them for 10 minutes in a large pot of water. Allow them to air dry.
Prepare the Brine: In a medium-sized pot, combine water, vinegar, and pickling salt. Bring the mixture to a boil, stirring until the salt is dissolved. Remove from heat and let it cool slightly.
Add Flavorings: Place garlic cloves, dill sprigs, black peppercorns, mustard seeds, coriander seeds, and red pepper flakes (if using) into each sterilized jar.
Pack the Cucumbers: Pack the prepared cucumbers tightly into the sterilized jars, leaving about 1/2 inch (1.25 cm) of space at the top.
Pour the Brine: Carefully pour the warm brine over the cucumbers, making sure they are completely submerged. Leave about 1/2 inch (1.25 cm) of headspace in the jar.
Remove Air Bubbles & Seal: Gently tap the jars on a counter to remove any air bubbles and adjust the cucumbers if needed. Top up with additional brine if necessary. Wipe the jar rims with a clean, damp cloth to ensure a proper seal. Place the sterilized lids on the jars and screw the bands on tightly.
Process: Process the jars in a water bath canner for about 10-15 minutes to ensure proper sealing.
Allow to Mellow: Allow the pickles to mellow in a cool, dark place for at least 2-3 weeks before opening to let the flavors meld and intensify.