Heat the olive oil in a cast iron skillet over medium-high heat. Add the onion and saute 3 minutes, until onion begins to soften. Add the chopped sweet potato and cook, stirring occasionally, until sweet potato is golden-brown and cooked through, about 12 to 15 minutes. Note: You can cover the skillet and reduce the heat to medium if your sweet potato is taking too long to cook.Transfer the sweet potatoes to a bowl.

Preheat the oven to 400 degrees F.

Add the chips to the cast iron skillet, followed by the cooked sweet potato, black beans, shredded cheese, and queso fresco. Bake in the preheated oven until cheese has melted, about 10 minutes. While the nachos are baking, cook 3 eggs on the stovetop to desired doneness.

Remove nachos from the oven and add the avocado, green onion, red onion, fresh cilantro, and salsa. Serve with sunnyside up eggs on top with additional salsa for dipping.