Chop the vegetables into medium-size chunks and Wash lentils.
Put stock into a 4-5 quart pot and bring to boil; add the onions, carrot, tomato and lentils to stock. Lower the heat to simmer and cook for about 1/2 hour or until the lentils are tender
Puree the mixture in either a food processor or blender and return to pot.
Saute the finely chopped onions in the olive oil until they are soft and brown.
Add the cumin, lemon juice, sauted onions, salt and pepper to soup and stir slowly over low heat for about 3 minutes