To make split pea soup you need one bag of split green peas. You will fill a pot with 4 cups of water and bring to a boil. Then you add in the split peas, carrots, onions, and potatoes. Bring everything to a boil and then reduce heat. Let it simmer for about 3 hours, stirring often. If you find it’s thickening too much you can add more water. I like to cut up leftover ham and put the ham bone in the soup when cooking.