No, not the fish! The cactus! Tuna is the Spanish word for prickly pear, or cactus fruit. They come in two colors, red and green, are full of seeds, and taste something like a melon.
They are also covered in spines. But, with the technique you are about to learn, that won't be a problem at all.
Step 1: What You Need
Oh, and a fresh, delicious prickly pear.
Step 2: Cut Off the Ends
Leave the fork in the fruit.
Step 3: Cut a Slit in the Skin
The cut needs to be through the skin, about a quarter of an inch deep. Too deep is better than too shallow, though.
Step 4: Peel the Fruit
At this point to can continue to peel the fruit with your forks, or hold the skin with a fork while you pull the fruit out with your fingers.
Either way, be careful not to stick yourself throwing the skin away.