In a large saucepan or 6 qt Dutch oven, cook the lentils as directed on the bag.
Once they have cooked for half the time indicated on the package, add the chopped onion, crushed garlic and chopped carrots. Stir in the undrained diced tomatoes and the juice from the lemons. Bring to bubbling, reduce heat and finish cooking the lentils.
Season with ground cumin and cinnamon.
When the lentils have cooked, remove from the heat to prevent the lentils from getting mushy.
Serve Lentil Stew warm with dollop of sour cream and cilantro in each bowl, with a side of pita chips.