In a pot, cover lentils with water and boil for 5 minutes. Drain.
Dry the pot, or in a different pot, cover bottom of pot with thin layer of olive oil. Place over medium heat, add lentils, stir to coat, then add about 6 cups of water.
Add tomatoes, onion, garlic, bay leaves and pepper. Bring to boil, then lower heat to simmer for about 40 minutes. Season with salt and pepper taste. Continue to cook until lentils are soft, but not mushy.
If soup seems too thin, remove a cupful and puree with immersion blender until smooth, the add back to the pot. To serve, drizzle with olive oil and sprinkle some crushed oregano leaves to taste. Decorate with sprig of fresh oregano if desired.