Using a towel or just holding it carefully, prepare 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.
Chop the clean nopales into small rectangles, rinse them in a colander, then simmer them in a large pot with water and salt until the nopales are tender and slightly darker green.
In the meantime, prep the tomatoes, onion, serrano, cilantro, avocado, and queso fresco. In a separate bowl, mix the zesty lime dressing.
After they’re cooked, transfer the nopalitos back to a strainer. Rinse them under cold water while vigorously mixing them to remove the slime. Combine the rinsed nopalitos with the tomatoes, onions, and serrano. Toss the salad with dressing, then top it with any of your favorite garnishes. Happy eating!