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.