I can't speak to cooking them, but I will tell you how I prepped it when I got it for the first time! I also am convinced I burned all the cals in a serving by cutting it all by hand!
I thinly sliced a medium-sized jicama into nice little slaw-like strips. This took forever. If you have a mandolin or food processor, I would use it :P I added half a bell pepper, cut similarly, and two mangoes, also thinly sliced into long thin pieces. The 'dressing' I made was lime juize, red wine vinegar, honey, fresh cilantro leaves, and a dash of salt and pepper.
It was *delicious* and sat well in the fridge for a couple days. I divided it into 4 servings- about 146 cals, .4 g fat, almost 2 g protein, and a whopping 10 grams of dietary fiber! I served it as a side to some yummy turkey burgers!
It kind of has the texture of a hard pear/apple... not sure how to describe it. I do think it would pair well with those fruits as well.
You can cook it- roast it or sautee it.