It is a south indian recipe which is made in many ways, most of them very elaborate and time taking.
Here is one simpler version.
1/4 cup tuwar daal / porotopalo in spanish(hulled and halved)
1/4 cup brown lentil (hulled and halved). In spanish it is called Lenteja and you get usually whole lentils locally. I just halve them in a vitamin dry jar and then wind-winnow to let go of the hulls
Tomatoes: 2 Medium size
Vegetables of your choice 1/2 cup chopped : Most favored vegetables are small onions, bottle gourd, okra, eggplant, drumstick(moringa fruit), carrot, potato, radish, bitter gourd. But you can add just about any vegetables available at hand.
Coriander seeds : We need dry coriander seeds, NOT coriander powder, NOT coriander leaves
Tamarind: Around 1 tablespoon
Salt, turmeric, grated ginger, chili powder(optional)
Soak tamarind in some water, to extract juice later.
Pressure cook/ boil/ steam cook the lentils to a thick paste.
Steam cook the chopped vegetables.
Roast the coriander seeds on low heat until the aroma releases. Remove from heat. Let them cook down. Grind to a powder. This is the most important spice of the dish.
Extract tamarind juice from the soaked tamarind (use the water in which it was soaked)
Mash the cooked lentils and add all ingredients together with salt, turmeric, grated ginger, 1 teaspoon of jaggery, tamarind juice, chili powder and 1 cup water. Boil on low heat for 5 minutes so that the spices get into the vegetables and the lentil soup.
Add spluttered mustard seeds, spluttered cumin seeds, curry leaves, chopped coriander, as garnish.
Serve hot with Idlis (an indian dish – steam cooked rice and black lentil dumplings) or rice or as is.