Steps
1. Rinse the red lentils under cold water until the water runs clear.
2. In a pot, heat the oil over medium heat and add the cumin seeds. Sauté until they start to splutter.
3. Add the chopped onion and sauté until translucent.
4. Stir in the chopped tomato, turmeric powder, red chili powder, and salt. Cook until the tomatoes soften.
5. Add the rinsed lentils and water to the pot. Bring to a boil, then reduce to a simmer.
6. Cook for about 20 minutes, or until the lentils are soft and mushy.
7. Blend the soup slightly for a creamy texture, if desired.
8. Stir in the lemon juice and garnish with fresh coriander leaves before serving.