In a large saucepan or Dutch oven, combine the lentils, water, garlic, carrots, onions, thyme, pepper, and rosemary. Bring to a boil over high heat. Reduce the heat to low, cover, and simmer, stirring occasionally, for 35 minutes, or until the lentils are tender. Stir in the tomato puree, salt, and cinnamon and simmer for 20 minutes to blend the flavors. Remove from the heat and stir in the oil, vinegar, and margoram or oregano (if using)