Set your Instant Pot to the sauté function. Heat the vegetable oil and sauté the onion, garlic, carrots, and celery until softened.
Add the rinsed green split peas to the Instant Pot, followed by the chicken broth, diced ham, bay leaf, and a pinch of salt.
Close the Instant Pot lid, ensuring the vent is sealed. Set the Instant Pot to cook on high pressure for 15 minutes.
Once the cooking time is complete, allow the pressure to release naturally for 10 minutes, then carefully do a quick release.
Open the Instant Pot, remove the bay leaf, and stir the soup. Check the seasoning and add salt if needed.
Serve the split pea soup hot, garnished with fresh parsley or croutons if desired.