Set a large pot over medium heat and melt the ghee. Toss in the onions, garlic, carrots, and potato, and cook, occasionally stirring, until they begin to soften, which should take about 7 minutes.
Incorporate the lentils, tomatoes, cumin, turmeric, and coriander into the pot, cooking for another 1-2 minutes until the mixture becomes aromatic.
Pour in the broth, and bring the mixture to a boil. Then, reduce the heat to low and let it simmer for 35-45 minutes until all the vegetables are tender (you can check the carrots for doneness).
In the meantime, prepare the croutons: Preheat your oven to 400°F. Cut the pita bread into small squares using scissors or a knife, or tear them by hand into bite-sized pieces. Drizzle olive oil generously over the pita pieces, sprinkle with salt, and arrange them in a single layer on a baking sheet. Bake for 10-12 minutes or until they turn golden and crispy.
Once the soup has cooked, use an immersion blender or a standard blender (in batches) to puree the soup until it reaches a smooth consistency. If you frequently make soup, investing in an immersion blender is a great idea, as it saves time and makes cleanup much easier.
Taste the soup and adjust the seasoning as needed. Serve hot, topped with the crispy croutons and a sprinkle of dukkah, if desired. You can also garnish fresh cilantro or parsley for added color and flavor.