Set the Instant Pot to the sauté setting. Add the olive oil and the onion and cook until translucent.
Add the asparagus and cook for 2-3 minutes until soft. Then add garlic and cook for about another 30 seconds, until fragrant. Stir in chicken stock, salt, and pepper.
Place on the lid and turn the valve to the sealing position. Set to manual pressure / high pressure for 5 minutes.
When done, allow a natural pressure release for 7 minutes and then perform a quick pressure release (QPR) to manually release any remaining steam.
Open the Instant Pot and allow the soup to cool for a few minutes before using an immersion blender, or transfer to a high-powered blender to blend until smooth.
Taste for seasoning and add more salt and pepper if needed.
Season with lemon juice and top with parmesan (if desired) before serving.