Add the lentils, bay leaf and approx. 750 ml water and bring to the boil. Simmer on medium heat for 30-40 minutes or until the lentils soften and the stew becomes creamy. If necessary add more water or vegetable broth.
Chop the parsley finely, season with salt, pepper and vinegar. Arrange in bowls and if you like serve with a dollop of yoghurt.