Heat the oil in a skillet; add sliced potatoes and diced onions. Cook slowly, medium flame. Turn occasionally until potatoes are tender.
Beat eggs in a large bowl with a fork. Salt to taste. Drain potatoes. Add potatoes to beaten eggs. Heat 2 tablespoons of the oil in large skillet. Add potato-egg mixture, spreading quickly. Lower the heat to medium-high. When potatoes start to brown, put a plate on top skillet and flit to cook other side. Adding another tablespoon of oil. Brown on the other side. Cook for about 2 more minutes.