The day before packing, bring the measured filtered water to a boil in a saucepan. Add the measured mineral salt, stir until dissolved and return to a boil. Remove from the heat, cover and leave overnight to cool completely. The brine must be cool or at room temperature before it touches the cucumbers.

Wash the cucumbers, trim a thin piece from the blossom end of each and rub away remaining blossom material or spines. Soak in ice water for 15 minutes. Set out a clean, dry quart glass jar and the measured seasonings.

Place one bay leaf near the bottom of the jar. Pack in the cucumbers, dill, garlic, mustard seeds and peppercorns, keeping two inches of headspace. Add the second bay leaf. Pour in enough cooled prepared brine to cover the solids. Use a clean, food-safe glass weight to keep them submerged. Do not dilute the prepared brine with plain water.

Fit a fermentation closure that releases gas, following its setup instructions, and stand the jar in a bowl or on a tray. Keep it in a cool place around 53–64°F (12–18°C), out of sustained direct sunlight. Check after a few days, keeping all solids under the brine. Look for developing sour flavor, olive-green skins and a more translucent interior; lid pressure is not the doneness test.

When the cucumbers taste pleasantly sour and retain a firm bite, refrigerate the covered jar. Three days is a planning allowance; the conditions and actual flavor/texture control. Keep the pickles under their brine, remove portions with a clean utensil and return the remaining jar to the refrigerator.