Set Instant Pot to saute, medium heat. Add olive oil, onions, and mushrooms. Saute for 5 to 6 min minutes until mushrooms are soft. Add garlic and chicken. Saute for 5 to 6 minutes. Turn off the saute setting. Add broth, wine, butter, tarragon, bay leaf, salt, and pepper to the pot. Secure lid and pressure cook on high, for 6 minutes. Allow the steam to release for 15 minutes, then manually release the remaining steam.

Remove bay leaf from soup. Mix xanthan gum with 1/2 tbsp olive oil until dissolved and add to soup. Stir until thickened. Add half and half and sour cream. Serve and enjoy!

Add chicken, onions, mushrooms, garlic, 1 cup broth, wine, tarragon, bay leaf, salt, and pepper to slow cooker and cook on low for 6 to 8 hours, until chicken is done and vegetables are tender. (Alternatively, you can saute the onions and mushrooms in olive oil in a skillet until tender before adding to crockpot if you want).

Remove lid and remove bay leaf. In a small dish, mix xanthan gum with 1/2 tbsp olive oil until dissolved, then add to soup. Stir in half and half and sour cream. Stir until thickened. Serve and enjoy!