In a large 6-quart Dutch oven add the olive oil and set over medium heat.
Add the chopped garlic, the mirepoix - onion, carrot and celery, along with the salt and sauté until the onions are translucent.
In a sauté pan toast the coriander and cumin seeds. When seeds start to pop and are fragrant take off the heat and grind in a spice grinder.
Add the lentils,
chicken stock
and spices to the vegetables. Increase the heat to high and bring to a boil. Reduce the heat to low, cover and cook at a low simmer until the lentils are tender, about 40 minutes.
Using a stick blender or Vitamix, purée half the soup mixture to your preferred consistency and pour back into soup. Add the chopped, roasted chicken and serve.