Place the inner pot inside the Instant Pot. Press Saute and set time to 10 Minutes. Add the olive oil and wait about 1 minute until hot. Add the leek and cook until slightly translucent.
Add the cubed chicken and sear on all sides, stirring from time to time so that they don’t burn.
Add the wine and let cook for 3 Minutes or until the alcohol is burned off.
Add the cream and mustard and stir to combine everything well. Press Cancel and add 1 tsp salt. Stir well.
It is important that the chicken remain covered in liquid. If necessary, add water or vegetable broth, if you have any, but not too much.
Close and lock the Instant Pot lid. Make sure the steam release handle is turned to Sealing. Press Pressure Cook and set time to 5 Minutes.
Once the time is up, press Cancel and turn the steam release handle to Venting. Once all the steam has been released, open the lid.
Serve hot with whatever side you like. You can garnish with parsley and a bit of pepper for a spicy kick.