After enjoying a watermelon, take large sections of rind and cut the watermelon rind into 1-2 inch wide segments. Then use a vegetable peeler to remove the green peel. You can leave some of the pink watermelon on the other side, but just a little bit. It tends to get mushy when pickled.
Now cut each section of rind into thin ¼ inch strips. (So the pieces for the jars should be ¼ in X 1-2 in)
Set out 4 pint jars. Place 5-7 jalapeno slices in each jar, followed by ½ teaspoon peppercorns.
Stuff the watermelon rind pieces in each jar. Make sure they are very full.
Set a medium saucepot over high heat. Add the white vinegar, water, sugar, and salt. Bring to a boil, stirring to dissolve the sugar and salt.
Once boiling, remove from heat and stir in the vanilla extract.
While the pickling brine is very hot, pour (or ladle) the liquid into the jars, making sure to completely cover the watermelon rinds.
Screw the lids on the jars and allow them to rest at room temperature. Once the jars are cool enough to handle, shake them vigorously to move the jalapenos around. Then chill for at least 2 hours, or overnight.
Keep refrigerated until ready to use.
Homemade watermelon pickles last in the fridge for about 4 to 6 weeks. After a month, the rinds start to lose that wonderful crunch.