Jungle Cactus
The Jungle Cactus have some of the best, most delicious of the many edible cactus fruit.
Some swear by the Peruvian Cactus Apple, but you can see here that the Dragon Fruit is going to be the best.
Hylocereus is the plant and they are a sprawling, climbing cactus that can get giant old trunks and branches climbing up fences and trees alike.
I understand they make a good Margarita.