Hit the 'saute' button on your Instant Pot (I have the 6-quart).
Add in the oil and let it warm.
Add in the onion and garlic, cooking for 1-2 minutes.
Stir in the celery, dill, salt, and pepper and hit the 'cancel' button to stop sauteing.
Pour in the water and lock the lid into place, making sure the release valve is set to 'sealing'.
Hit 'manual' and set the timer to 12 minutes on high pressure.
Once the pot beeps, let the pressure naturally release for 10 minutes (meaning, don't touch anything!). It will read LO10.
Release the remaining pressure.
With an immersion blender, puree the soup to your liking.
Taste for extra salt and pepper.
Be sure to serve with fresh lemon wedges, as the juice really brings out the flavor!