How to make
Pour the lentils into a pot, pour on water and boil for 10 min. Strain it.
Heat 2 tbsp of olive oil in another pot and braise 2 of the onion heads with the garlic, cumin and turmeric. Add the lentils, broth and 2 1/2 cups water.
Bring to a boil, lower the heat and boil for 30 min. Braise the 3rd onion head in the remaining olive oil.
Season the soup with salt and black pepper, pour it into bowls, sprinkle with coriander and the braised onion and serve right away.