If the turkey breast is frozen, let thaw in refrigerator for 3 days in the wrapping it came in. Remove the gravy mix, if any. Rinse the turkey breast and let it drain in a colander. Pat it dry with paper towels. Loosen the skin on top of the breast with your fingers and a knife but do not cut it off.
Combine butter, herb seasoning, and salt in a small bowl. Using fingertips, spread about 2 tablespoons of the mixture up under the skin and onto the turkey breast. Lay the skin over the mixture then spread the remaining mixture on top of the skin.
Place the trivet in the Instant Pot 6 qt Duo pan and pour in chicken broth.
If the turkey breast has a cavity on the top, place the onion and celery there. If it is open, just place them in the Instant Pot around the turkey breast in the pan. The turkey breast is placed breast side up in the pan.
Place the lid on the Instant Pot and set valve to “sealing”. Press “Pressure Cook” button, then -/+ button to 32 minutes on High Pressure. It will take about 12 to 20 minutes to come to pressure, cook 32 minutes, then when it beeps, let it release pressure naturally (don’t touch sealing valve) for 20 minutes. If it hasn’t release all the pressure, switch to “venting”. Carefully open the lid away from your face when floating valve drops.
Preheat broiler. Remove the turkey with two large metal spatulas or spoons. Forks will release all the turkey juices! Place it on a foil-lined baking sheet and broil it 3 to 5 inches from the broiler for 3 to 5 minutes or just until skin in golden brown.
Measure 2 cups of turkey drippings in the Instant Pot pan. Discard any remaining liquid, onion and celery (I actually save them for soup later). Combine 1 tablespoon water and cornstarch in a custard dish then pour into turkey drippings. Turn on the “Saute” button. Cook the gravy, stirring constantly about 8 minutes or until slightly thickened. Yield: 6 to 8 servings.