A knife set for removing thorns from the surface of the nopal cactus petal which, in one aspect, is comprised of a cutting tool with a handle and a curved cutting blade extending out of a handle member. The handle is configured in a plane that is elevated above the average longitudinal axis of the curved blade allowing for the thorn removal without exposing the user's thumb and fingers to being cut and injured on the cactus petal prickers. The curved cutting blade has sharpened edges that extend the length of the blade and terminate in rounded corners at the blade end to prevent the cutting end from gouging and tearing the surrounding edible petal tissue. Another aspect of the disclosure comprises a securing tool having a curved blade that is generally perpendicular to the direction of the handle. The securing knife is used in combination with the cutting knife and is positioned against the cactus petal surface, near the base, to prevent the petal from shifting in location during the dethorning process. A third aspect of the disclosure relates to a method of dethorning the cactus petal using the cutting knife and the securing knife in combination.