First, prepare your cucumbers by washing them thoroughly and quartering them lengthwise into spears.
In a large non-reactive pot, combine the cider vinegar, water, sugar, salt, and bay leaf.
Place the cloves, celery seeds, peppercorns, mustard seeds, and ½ teaspoon of the dill seeds into a small muslin spice bag and add it to the pot. If you're using fresh dill, omit the dill seeds from the spice bag.
Bring the brine mixture to a rolling boil, then reduce the heat and let it simmer gently for 15 minutes to allow the flavors to meld.
While the brine simmers, prepare two clean quart-sized canning jars.
Place ¼ tsp of the remaining dill seeds (or 1 head of fresh dill) into the bottom of each jar.
Remove the bay leaf and the spice bag from the hot brine and discard them.
Tightly pack the cucumber spears vertically into the prepared jars. You want them to be snug but not crushed.
Carefully pour the hot vinegar mixture over the cucumbers in each jar, ensuring they are completely submerged. Leave at least a ½-inch of headspace at the top of the jar.
Wipe the jar rims, secure the lids, and process the jars in a boiling-water bath for 20 minutes.
Carefully remove the jars from the water bath and let them cool completely on a towel.
Check that the seals are firm, then label and store your pickles in a cool, dark place.