Soak lima beans in water overnight.
Skin and place lima beans in a large pan and cover with water. Cut 1 onion in half and add to lima beans together with pork skin. Bring to a boil and continue cooking until lima beans are very soft and almost melt. Remove onion and pork skin.
Heat olive oil in a large skillet. Chop remaining onion and cook in oil until translucent. Add lima beans and boil for 20 minutes. Season with salt and pepper and cook for 15 more minutes. Drizzle olive oil on top and serve with white rice.