In large non-stick skillet cook cactus with minced garlic and garlic salt. Let it cook in it's own juices. Once in a while mix cactus so they all cook until dry.
While cactus is cooking, start cutting up onions, tomatoes, cilantro, and chilies to desired size, and set aside in med-large bowl.
Once all veggies are cut up and cactus is dry, mix all ingredients together. This can be used as an appetizer served with chips, or it can be used as a side with some carne asada (bbq) yummy! Of course add or omit chilies according to your spicy preference :)