Peel and mince garlic. Rinse the cilantro, pluck the leaves and finely chop.
Heat 1 tablespoon ghee in a saucepan. Saute the cumin, turmeric, paprika and chili together until fragrant. Rinse the tomatoes, halve, remove seeds and dice. Add the tomatoes to the saucepan.
Add the lentils and stir to combine. Add 1.2 liters (approximately 5 cups) of water and bring to a boil. Reduce the heat and simmer, covered, for about 25 minutes. The lentil curry should not be dry, add more water during cooking if necessary.
Season the soup with salt and sugar. Serve in bowls garnished with cilantro leaves.