Place the celery, onion, herbs and broth in Instant Pot and arrange a steamer trivet on top.
Arrange turkey breast on top of the trivet and sprinkle with salt and black pepper.
Secure the lid and turn to “Seal” position.
Cook on “Manual” with “High Pressure” for about 30 minutes.
Press “Cancel” and do a quick release.
Remove the lid and transfer the turkey breast onto a cutting board.
With a slotted spoon, skim off the fat from the surface of broth. Then strain it, discarding solids.
In a small bowl, dissolve the cornstarch in water.
Return the broth in Instant pot and select “Sauté”.
Add the cornstarch mixture, stirring continuously and cook for about 3-4 minutes.
Select “Cancel” and transfer the gravy into a serving bowl.
Cut the turkey breast into desired sized slices and serve alongside the gravy.