Prickly pear can be used as a vegetable, sharpen the edge of a spoon and scrape of the thorns, then thinly slice and cook. It is only a cactus and this is how the Mexicans do it.
The fruit is also delicious, using rubber gloves rub of the fine prickles in cold water, cut open and scoop the flesh out.
Good emergency food.
This I just found and is interesting, the prickle pear is the actual fruit but in Australia came to be recognised as the whole cactus plant because we were not use to cacti at that point in our history. http://www.foodreference.com/html/art-cactus.html