Clean the nopales by cutting around both edges to remove the outer thorns. For the rest, run the edge of your knife in a horizontal fashion all over the paddle until the thorns are gone. Flip and repeat on the second side.
Chop the de-spined nopales into small rectangles, rinse them in a colander, then place them in a large pot with water and a large pinch of salt. Bring the mixture to a boil, then lower the heat to simmer for 15 minutes, or until the nopales are tender and slightly darker green in color.
In the meantime, prep the tomatoes, onion, serrano, cilantro, avocado, and queso fresco.
After they’ve cooked, transfer the nopalitos back to a strainer. Rinse under cold water while vigorously mixing to remove the slime. Add the rinsed nopalitos to a mixing bowl, then stir in the tomatoes, onions, and serrano.
In a separate bowl, mix the lime juice, olive oil, Mexican oregano, salt, and pepper. Mix together, then combine the dressing with the nopales salad.
Serve your cactus salad with cilantro, queso fresco, and avocado on top. Happy eating!