Sauté onion and chili peppers. Heat oil in a large cast-iron pan over medium heat. Add onions and peppers and saute until onions become translucent, for about 3 to 5 minutes.
Add tomato. Add the tomato and cook for an additional 3 to 5 minutes to absorb some of its moisture.
Add eggs. Crack the eggs into a bowl, season with salt, and whisk well. Add the whisked eggs to the pan and mix with the other ingredients, then reduce heat to low and cook until the eggs reach your desired consistency. I like mine cooked through, but not dried out or burned. The entire process can take anywhere from 3 to 10 minutes, depending on how you like them. Remove eggs from heat, especially if you are using a cast-iron pan because they will continue to cook.
Serve and enjoy. To serve, heat tortillas on a comal or flat pan, then prepare each taco with two to three tablespoons of the scrambled eggs mixture and top with a sliced avocado, shredded cabbage, and your favorite salsa. Alternatively, you can serve your eggs alongside refried beans, or wrapped into a flour tortilla.