Wrap washed potatoes in damp paper towels and place on a microwave safe plate. Microwave 3 minutes at a time, checking for doneness. Potatoes should be tender but still firm.
Heat oil in a large cast iron skillet over medium heat. Add the potatoes and allow them to cook undisturbed for 3 mins. Use tongs to turn each potato. Add the chopped onions and cook 3 mins more.
Cook potatoes 5 more minutes, turning frequently. Once golden to your liking, transfer to a baking sheet lined with paper towels to remove excess oil and set aside.
While the beans are cooking, crack the desired amount of eggs into a bowl and whisk. Heat a non-stick skillet over medium heat and add 1 tbsp of butter per 2 eggs you plan to cook.
Once butter is melted, pour in the eggs and use a rubber spatula to continually pull the eggs toward the center until just set. Turn off the heat and top eggs with grated cheddar cheese. Add potatoes, avocado, beans & salsa. Enjoy!