Wash and sort the pepperoncini. Using a sharp knife, make a split in the side of each, keeping the stem in tact.
Wash and sterilize 4 - 16 ounce canning jars. Simmer the tops in water. Set a large canning pot to boil.
In a large heavy bottomed pot, add 4 cups white vinegar and 4 cups water with 1/4 cup kosher or pickling salt and 1/3 cup sugar.
Bring the mixture to a boil, then remove from the heat.
Stuff the jars with pepperoncini. **And I mean stuff! These peppers are going to shrink a lot in the water bath, so the more you can fit in the better they'll be.
Crush 2 cloves garlic into each jar. Add 6-7 whole pepper corns and 6-7 whole coriander seeds, 1 tsp dried, crushed red pepper flakes and 1 bay leaf(if using) .
Fill the jars to about 1/4 inch head room, then add the tops and then the rims, and close, but not too tightly.
Process for 10 minutes in boiling water with at least 2 inches of water above the rims.
Once done, let the jars sit, covered for 5 minutes.
Remove the jars from the canner and let them sit, undisturbed for 24 hours.
Any that did not seal can be refrigerated and eaten with a few weeks. Properly preserved, you can store the pepperoncini for up to a year. Refrigerate once opened.