1. 1. Saute onions with olive oil in a large stock pot until translucent on medium heat, which will take about 8 minutes.
2. 2. Add celery, carrots and potato and saute 3-4 more minutes.
3. 3. Pour in chicken broth and add split peas and ham. Uncovered, bring to a boil.
4. 4. Once boiling, cover and turn heat down to low. Let the soup simmer for 3-4 hours. The soup is done when the split peas have broken apart and are evenly mixed throughout the soup.
5. Notes: The longer you cook the soup, the better and more developed the flavor gets-sometimes I'll transfer it to a crock pot and let it simmer in there all day. If you like a smooth soup, blend finished soup with an immersion blender or in a food processor in small batches (large batches will make a mess!) If you like a thicker soup, add a small hand full of split peas to the 1-cup listed.