Pour lentils into a large mixing bowl and cover with hot water by two inches. Stir in vinegar, cover with a kitchen towel, and allow the lentils to soak for eight to twelve hours. After they’ve soaked for eight to twelve hours, drain off the water and rinse them well.
Preheat the oven to 425 degrees Fahrenheit. Arrange tomatoes and eggplant on a baking sheet, drizzle with olive oil and roast at 425 degrees Fahrenheit for about thirty minutes or until the tomatoes begin to caramelize.
Melt ghee in a heavy-bottomed stock pot and stir in onion. Fry the onion in ghee until it softens and becomes translucent, six to eight minutes, then stir in mustard, cumin and coriander.
Pour chicken stock into the pot over the onions and stir in soaked lentils. Cover and simmer until the lentils are tender, about twenty minutes. Once the lentils are tender, stir in roasted tomatoes and eggplant and continue simmering, covered, for a further twenty to twenty-five minutes.
After twenty to twenty-five minutes, turn off the heat, stir in the kale and cover. Allow the kale to wilt under in the ambient heat of the soup. Season the soup to taste with unrefined sea salt (see sources), coarsely ground black pepper, and additional olive oil.