Add the oil to the cooker over medium heat. Sauté the leeks for about 3 minutes, add-ing water if they begin to stick. Add the pota¬toes, broth, thyme, bay leaves and salt, standing back to avoid sputtering oil.
Lock the lid in place and bring to high pres¬sure over high heat. Reduce the heat to main¬tain high pressure and cook for 4 minutes.
Reduce the pressure with the quick release method. Remove the lid, tilting it away from you, to allow any excess steam to escape.
Remove the bay leaves. Pureé the soup with a hand blender until it is the desired con-sistency, or remove some of the potato mix¬ture and pureé carefully in a blender or food processor. (This can be done in the blender by filling the container half full or less, cover¬ing the top of the container with plastic wrap, putting the lid on and covering that with a towel.)
Taste the soup once blended, adding salt if necessary. Garnish with chopped Italian pars¬ley or chive flowers, if you have them.