It looks as though this recipe is complicated. It's not. It takes 3 days, but none of the techniques is complex. And the result is sooo good!
Here is the recipe, divided by the number of pounds of raw watermelon rind.
(pounds of rind) (from how much watermelon) (vinegar) (sugar) (spices)
(5) (half a large melon) (2 1/2 c) (5 c) (1/2 c)
(10) (large melon) (5 c) (10 c) (1 c)
Here's the method.
Prepare the raw watermelon rind by peeling it as little as possible. Take off only the dark green outside layer. Leave as much of the rind (white part) as you can. This is the part from which the pickle is made. Trim off the pink and red parts.
Cut the rind in cubes no larger than 1" on a side. You'll have some odd-shaped pieces, and this is ok, too.
Make a salt brine from 1 quart of water and 1/2 c table salt. Make enough brine to cover the rind. Put rind in, cover, and let stand overnight.
Drain and rinse rind.
Put rind in a large pot with water to cover and boil until rind is just tender.
In another pan, combine sugar, vinear, and pickling spices. Bring to a boil and boil 5 minutes.
You probably will want to remove the spices before jarring, but it's not necessary.
It just makes serving easier because you don't have to pick off the spices. 1/4 c of spices will fit in teaball. If you prefer, cut a length of cheesecloth (buy this at the grocery store) and fold to make a double thickness. Put spices on this and tie up with cotton kitchen twine or white pearl cotton.
Drain rind and add to spice syrup. Syrup must cover rind. Make more syrup if needed. Let cool and then cover.
Let stand 8 hours.
Bring rind and syrup to a boil.
Place in sterilized jars with sterilized lids, filling to overflowing with the syrup.
To sterilize jars and lids (even new ones you've just bought), put 2" of water in a large pot and place the jars in, open side down. Just drop in the lids (and rings if this is the kind of canning jars you've bought). Boil 10 minutes, topping up with boiling water (so the temperature doesn't drop) as needed.
Follow instructions that come with the canning lids. If you don't get a good seal on any of them, store in the refrigerator.
I have successfully used jars that jelly and pickles come in commercially, although you're not supposed to do this. These jars must have the "rubber" seal on the lid in perfect condition, however.
If the top of the lid pops down in the course of cooling after jarring (or stays popped down when you press on the middle of the lid), chances are you have a seal. (In any canning or pickling when the product will not be refrigerated, if the lid doesn't pop down, your seal is faulty and the product will spoil.) Properly canned pickles will last years and years. If the product turns black or the lid is no longer popped down, you'll know they're no longer good. Pitch them.
If this is your first try at canning, please consult a good cookbook (such as Fanny Farmer or Joy of Cooking) or a canning book for basic and detailed information. This information is on the web at most states' land-grant colleges' home extension sites.