Heat olive oil in a large pan or skillet to medium heat. Add onions and salt, cook 4–5 minutes, stirring often.
Reduce heat to low and continue to cook; stirring occasionally. Cook for at least 20–25 minutes. You may need to add more oil to prevent from sticking. Onions are done when they are browned (or caramelized) and softened. See photos above for details and step-by-step instructions.