Boil the shanks together with garlic, onions, bay leaf, rosemary and black peppercorns for about 2.5 hours or until the meat is completely soft. In the beginning watch the soup to remove the froth as it forms.
While the broth is cooking, use a big bowl to wash the chana dal, cover with water and leave it to soak.
In another bowl, thoroughly rinse masoor dal a few times.
When the lamb is completely cooked (soft and falling off the bones), discard the onions, garlics, rosemary and bay leaf and transfer the shanks to a large board.
Add the carrots and the rinsed chana dal to the broth and bring to simmer. There will be more froth, keep removing it. After about 10 minutes pop in the small red lentils and strained tomatoes. Salt to taste.
Continue to simmer until the lentils are cooked. In the meantime, pull the meat off the bones and add it back to the soup in the very end.
Squeeze over a lemon wedge, season with black pepper and serve with fresh bread.