Note: I copied this word-for-word from the print-out of the USDA recipe I was given in my MFPC class. It's written a bit differently than my usual recipes, but I thought it was important to note this fact. It is called "Bread-and-Butter Pickled Jicama" in their bulletin.
The only exception? I added salt, but you can leave it out if you wish.
The following italicized head-note is my own:
I've never thought to pickle jicama, but I'm not sure why. I've always like the fresh texture of jicama root, and that very quality is what makes them perfect for pickling. They keep their satisfying crunch, even after being processed in a boiling water bath canner. The classic sweet-tart brine known as Bread & Butter-style is always a hit for family get-togethers and gift-giving, so make extra if you have access to good quality jicama. Serve them like you would any other type of pickle. All you really need to enjoy these tidbits is a toothpick.
Yield: about 2 pint jars.
Procedure:
1.) Wash and rinse canning jars and keep hot until ready to use; prepare lids according to the manufacturer's instructions.
2.) Combine vinegar, sugar and spices in a 12-quart Dutch oven or large saucepot. Stir and bring to a boil. Stir in prepared jicama, onion slices, and red bell pepper. Return to a boil, reduce heat and simmer 5 minutes. Stir occasionally.
3.) Fill hot solids into hot pint jars, leaving 1/2-inch headspace. Cover with boiling cooking liquid, leaving 1/2-inch headspace. Remove air bubbles and adjust headspace if needed. Wipe rims of jars with a dampened clean paper towel. Apply two-piece metal canning lids and process.
4.) Process in a Boiling Water Bath Canner according to USDA recommendations*. Let cool, undisturbed, 12-24 hours and check for seals.
*0-1000 ft: process 15 minutes
1,001-6,000 ft: process 20 minutes
Above 6,000 ft: process 25 minutes
Bread & Butter-style Pickled Jicama blog post