Rinse and soak both lentils in warm water for 20 minutes then discard the water.
In a pot take soaked lentils with 4 cups of water, and add onions, tomatoes and all spices. Bring it to boil then cover the pot. Cook for 20 minutes on medium heat until very soft.
Mash lentil for 5 minutes until it form a puree. Add water as required until desired consistency is reached. (You may blend it with an immersion blender.) Continue to cook on low heat.
For tempering
In another pan, fry sliced onions until slightly golden, then add all ingredients of tempering and fry for 1 minute.
Add the tempering to the lentil pot and cover immediately. Simmer for 5-10 minutes. Finally, garnish with chopped cilantro and chilies. Serve hot.
Notes
Lentils: Both lentils can be easily found in most superstores and Indian stores.
Dry red chili: I used button red chili, but you can use any dry red chili you like. Our fresh chili would do the job. If you have curry leaves in hand, they also taste great in tempering.
Garnish: We like cilantro and chilies for garnish because we love spicy food. You may add butter as well.
I used a mix of yellow and red lentils in equal; proportions. But actually, you can use just red lentil (250 gram) or just yellow lentil (250 gram) and follow the recipe as it is.
You can skip soaking (I do it often when making daal unplanned.
Served it with rice, roti, lemon pickle, and fresh kachumber salad.