Trim and clean the Nopales by removing edges and any remaining spines, then rinse them under cold Water. Slice the paddles into 1/2-inch strips or bite-sized pieces.
Place the sliced nopales in a large pot, add enough Water to cover, a halved White Onion, a lightly crushed clove of Garlic, and about 1 teaspoon Salt. Bring to a boil, then simmer 10–15 minutes until the nopales are tender and some of the sliminess has cooked away.
Drain the nopales and rinse under cold Water to remove excess slime and cool them quickly; squeeze out any excess liquid and chop more finely if desired.
In a large bowl combine the cooled nopales with diced Roma Tomatoes, finely chopped remaining white onion, seeded and minced Jalapeño (to taste), and chopped Cilantro.
Make the dressing by whisking together freshly squeezed Lime Juice, Olive Oil, a pinch of Salt and a sprinkle of Dried Oregano; taste and adjust acidity or salt as needed.
Gently fold the dressing into the nopales mixture, then add diced Avocado and crumble Queso Fresco over the top. Toss lightly to combine so the avocado holds its shape.
Let the salad rest 10–15 minutes for flavors to meld, then serve chilled or at room temperature as a side, taco topping, or light main.
