Chop onion, celery, and carrot and place in a bowl.
Chop ham into chunks and set aside.
If using a Ham Bone, you don't need to chop off the ham that is on the bone.
Rinse dried peas, drain and set aside. (They will stick together when added to the InstaPot, which is normal.)
Turn on the InstaPot to the Saute setting, and add oil.
Saute the onion, celery, and carrots a few minutes to soften.
Add salt, ground pepper, chopped ham, chicken broth, and split peas. Stir to combine.
Set Pressure at high and set timer for 15 minutes. Cover and cook, letting it natural release for about 15 minutes.
Once the soup is done, you can puree it with a immersion blender if desired.