Soak the lentils for at least an hour (it really helps to cook the lentils faster) and cook till mushy.
Meanwhile, sauté and caramelize half the onions and keep aside. Fry the remaining half onions till crispy brown but not burnt.
Once the lentils get cooked, mash well and add the caramelized onions, ground cumin, chicken stock and cook on low heat for another 10 minutes. Season with salt and pepper. The consistency of this soup is quite runny but you can add less stock/water and thicken it up.
Remove from heat and add lemon juice. Add one tsp, taste and keep adding till the right balance of sour, salty and sweet has been achieved. I like the tang and used about 2 tbsp but it might vary according to your taste preferences.
Garnish with crispy fried onions.
Serve hot with bread.