Rinse lentils in cold water in a colander or strainer and drain.
In a soup pot, sauté vegetables and garlic in olive oil for 2-3 minutes, until wilted.
Add lentils, water, tomato paste, parsley, and bay leaf. Bring to a boil and simmer covered for 45 minutes, or until lentils are tender.
During the last 15 minutes, add a big pinch of salt. Stir in lemon juice and sprinkle with oregano just before serving.
