Wash the lentils well with plenty of water and let them drain in a strainer.
Put a pan with oil on medium-high heat. When the oil is hot, add the chopped onion and a pinch of salt.
Fry until golden and add grated ginger or ginger paste, turmeric, and cumin powder. Add a splash of water so that the spices do not burn. Fry for a few seconds.
Add the chopped tomatoes and continue frying. Then add the red lentils, mix everything, and stir fry for a minute.
Add water and salt. Let it cook on medium heat for 15-20 minutes.
Then, with a whisk stir the soup very well to break the lentils to get a homogeneous texture and continue to cook.
Meanwhile, make the Tadka. Heat a small frying pan over medium flame and add oil.
When the oil is hot, add dry red chillies and cumin seeds.
When they start to sizzle, lower the heat and add turmeric and red chilli powder. Give them a quick stir and add directly to the cooked lentil. This whole process must be done very quickly without burning the spice powder.
Stir everything well and sprinkle with freshly chopped coriander. Let it simmer on low heat for 5 minutes.
Serve hot with rice or Chapati.
