Set the Instant Pot to saute mode and add the olive oil. Add the diced onion, carrots, and celery, cooking for 4 minutes until the vegetables begin to soften. Add the garlic and cook for 30 seconds.
Add the rinsed split peas, smoked ham hock, chicken broth, dried thyme, bay leaves, salt, and black pepper. Stir everything together.
Lock the lid and set the valve to sealing. Pressure cook on high for 15 minutes.
When the cook time is complete, allow a natural pressure release for 10 minutes, then carefully switch the valve to venting to release any remaining pressure.
Remove the lid and take out the ham hock and bay leaves. Once the ham hock is cool enough to handle, pull off all the meat, chop it into small pieces, and return it to the soup. Discard the bone and any fat.
Stir the soup well. The split peas will have broken down into a naturally thick and creamy texture. Stir in the lemon juice, then taste and adjust salt and pepper as needed.
Ladle into bowls and serve with crusty bread on the side.