In a large pan, drizzle olive oil over medium low heat. Add the onions and cook, stirring occasionally until lightly golden and caramelized, 20-30 minutes. Adjust the heat as needed to keep them from browning. They will continue to darken as the potatoes cook.
While the onions caramelize, place the cubed potatoes in a colander and sprinkle with salt. Toss to coat. Allow to rest for 5 minutes. Rinse and drain.
Place the prepared potatoes in the pan with the caramelized onions and drizzle with 2 tablespoons water. Immediately cover the pan and allow to cook, stirring occasionally, until nearly tender, about 15 minutes. Toss with the cumin and season with salt and pepper.
If needed, drizzle the pan with a little more olive oil and increase the heat to medium to brown the potatoes, tossing often.
In a medium bowl, beat the eggs with a pinch of salt. Pour the eggs into the pan and cook, stirring often to scramble just until set.
Remove from heat and adjust seasonings to taste. Serve immediately with fresh cilantro.