Set the Instant Pot to Sauté mode, add olive oil, and sauté onions for 2 minutes until soft.
Stir in garlic and cook for 30 seconds until fragrant.
Add potatoes, carrots, vegetable broth, salt, and pepper. Stir well to combine.
Close the lid, set the valve to Sealing, and pressure cook on High for 5 minutes.
Allow natural pressure release for 10 minutes, then manually release any remaining pressure.
Open the lid, stir in butter, and garnish with fresh herbs and green onions.
Taste and adjust seasoning if needed.
Serve warm as a side dish or enjoy on its own!