For the spice paste, clean and seed 1 chilli pepper. Fry briefly with coconut shavings and coriander in a hot pan without fat. Let it cool down and crush it in a large mortar. Gradually stir in 100 ml water.
Peel and finely dice the onions. Boil up with lentils, turmeric and ground chilli in 3/4 l water. Cover and simmer for 10-12 minutes until the lentils are soft.
In the meantime, peel and wash the carrots and potatoes and cut them into small pieces. Add to the lentils with the frozen beans and bring to the boil again. Cover and simmer for about 10 minutes.
Meanwhile, to sprinkle 2 chillies and the curry leaves finely chop. Heat the oil in a frying pan. Roast the mustard seeds for 2-3 minutes while stirring. Fry the curry leaves and chillies briefly.
Stir tamarind paste and 4 tablespoons of hot water until smooth. Stir the spice paste from the mortar into the lentil vegetables. Season to taste with salt. Serve the Kootu Sambar and sprinkle the roasted spices over it.
Roti (Indian flat bread) goes well with it.