This is a good way to use leftover ham, quite inexpensive, and VERY tasty. I hope that you enjoy it.
Some people like to add carrots or other types of vegetables.
In a medium pot, saute onions in oil or bacon grease. Remove from heat and add split peas, ham bone or chopped ham. Add enough water to cover ingredients, and season with salt and pepper. While it is cooking, check to see if water has evaporated. You may need to add more water as the soup continues to cook.