Heat oil in a large skillet, add onions and cook, stirring, until translucent, about 2 minutes.
Add the nopales and let them sweat and darken for about 5 minutes, stirring once or twice. They may exude a gelatinous liquid that will begin to dry out.
Add tomato and stir for another 2 minutes.
Meanwhile, in a medium bowl whisk eggs and then add them to skillet and cook for 2 to 3 minutes or until eggs are cooked thoroughly.
Serve with salsa of your choice and corn tortillas.
Notes
Don’t Go Too Hot. You want the pan to be hot, but not scorching, by the time you add your eggs. If your oil is starting to smoke, that’s a sign to remove the pan from heat for a few minutes to cool down, then return it to a lower flame.
Use Shortcuts. Purchasing pre-prepped cactus and frozen chopped onions makes this recipe for nopales come together extra fast.
Practice Patience. When it comes to cooking with nopales, some recipes call for boiling or soaking them nopales in salted water beforehand to eliminate the baba slime. This recipe eliminates that step, instead adding them to the skillet raw. I would recommend you cook the nopales thoroughly and allow any gelatinous liquid to cook off in the skillet before adding the eggs.