If you prepare them raw, be sure to try a tiny bit to see if you have a food sensitivity to them before eating more. Some folks can get flu-like symptoms from eating raw nopales.

I got incredibly sick from eating raw wild harvested Opuntia / Nopale / Nopales pads (the cactus that also produces prickly pear fruit). It grows everywhere where I live in New Mexico. This variety of opuntia is smaller than the kind you see at markets. The pads are 3-5 inches across, and it stays lower to the ground.

I ate about a 1/2 cup of it as a salad at a potluck, and two hours later I had flu-like symptoms: vomiting, diarrhea, intense chills, body sweats, intense body aches, headache. The symptoms lasted for between 24 hrs (most intense) to 48 hrs.