In a large bowl, cover lentils with boiling water and let stand for 15 minutes. Drain.
In a large stockpot on medium heat, sauté the onions, leeks, and garlic with the olive oil, salt, pepper, thyme and cumin for 20 minutes or until the vegetables are translucent and very tender. Add the celery and carrots, sauté for 10 more minutes.
Add the vegetable stock, tomato paste and lentils. Cover and bring to a boil. Reduce the heat and simmer uncovered for 1 hour, until the lentils are cooked through. Check the seasonings.
Nutrition Information(per serving)
Calories: 150 Fat: 3 g Sodium: 285 g Fiber: 9 g Protein: 8 g
Sprinkle with grated Parmesan Cheese (not included in nutritional analysis)