Cut the ends of the Leeks of and slice (but not right through) down the middle. Run them under the tap with the green ends at the bottom. Make sure you part the layers slightly to allow the water to run through and remove any dirt.
Chop the washed Leeks.
Crush the Garlic.
Remove the lid from your pressure cooker and add the Olive Oil.
Stew (using Stew function) the Leeks and Garlic for a couple of minutes.
Add the diced Potatoes and stew for another minute.
Add the Stock.
Cancel the Stew setting.
Close the pressure cooker and set the valve to Closed.
Set the Soup setting to 6 minutes.
When the time is up, Cancel the Soup setting and set the valve to Open (Be very careful, as steam will come out immediately. I use a wooden spoon to flick the valve open).
When all the steam has been released, open the lid and blend with a stick blender. I like to leave a few lumps and bumps, but you can blend it as smooth as you like. Add the Dijon mustard here, if you want to.
Add enough Crème Fraiche to make it as creamy as you want it. A tablespoon per portion is a good starting point.
Stir the Crème Fraiche until it blends or just swirl it around near the surface, whichever you prefer. The Crème Fraiche may cool it slightly, but the soup will be so hot it will probably make it the correct temperature for you. If you feel you need to reheat it then transfer to a saucepan and gently heat it.
Serve on its own or dunk in a piece of crusty bread.