Add the oil. Let heat for 30 secs and then add the onion and celery. Saute for 1 min and then add the carrot and the sweet potato. Add the salt, thyme, garlic powder, italian seasoning, white pepper (if adding) and black pepper (if adding). Stir to mix well with the veggies. Then add the chicken pieces. Pour the water and close the lid. Make sure valve is in sealing position.
Press Cancel and then press 'Pressure Cook' and set pressure cook time to 5 minutes.
Once pressure cooking time is done, release pressure manually and then open the lid. Using a large ladle, transfer the chicken pieces onto a large mixing bowl.
Using two forks, shred the chicken completely. Transfer back to the Instant Pot.
Add the coconut milk and the kale. Stir to mix and press saute button again. Let cook for 5 mins (uncovered - do not place lid back).
Meanwhile, in a small bowl, mix the arrowroot starch with the water until it forms a smooth slurry.
Pour this slurry into the Instant Pot and stir slowly using a wooden spoon for about 2-3 minutes until you can feel the sauce thicken. Press 'Cancel' button.
Check soup for seasoning and add more salt if needed. Transfer soup to serving bowls.
Notes
I like to use white sweet potato in this recipe since it holds up to the pressure cooking. Regular sweet potato tends to turn mushy with pressure cooking.
Recipe by Cook2Nourish at https://cook2nourish.com/2020/05/instant-pot-creamy-chicken-and-vegetable-soup-paleo-aip-whole30.html