From The Barefoot Contessa Cookbook, adapted slightly. Serves 8-10.
1 lb French green lentils (or brown lentils)
4 cups chopped yellow onions (3 large)
4 cups chopped leeks , white part only (2 leeks)
3 cloves garlic, minced
1/4 cup olive oil
1 Tbsp kosher salt
1-1/2 tsp fresh black pepper
1 Tbsp minced fresh thyme, or 1-1/2 tsp dried thyme leaf
1-1/2 tsp ground cumin
3 cups diced celery
3 cups diced carrots
3 qts chicken stock, homemade or low-sodium store-bought (or vegetable stock)
1/4 cup tomato paste
4 Tbsp red wine (or red wine vinegar)
Freshly grated Parmigiano-Reggiano cheese (optional, for topping)
In a large bowl, cover the lentils with boiling water and allow to sit for 15 minutes. Drain. (Skip this step if using regular brown lentils.)
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, until the vegetables are translucent and very tender. Add the celery and carrots and sauté for 10 more minutes. Add the chicken stock, tomato paste, and lentils. Cover and bring to a boil. Reduce the heat and simmer, uncovered, for one hour, or until the lentils are cooked through (if you're using regular brown lentils, check for doneness at 45 minutes). Taste, and adjust seasoning with salt and pepper as needed.
Add the red wine or wine vinegar and serve hot, sprinkled with grated cheese (optional).