Wash the moong and toor Daals well and cook in a pressure cooker adding adequate water, salt and turmeric powder.
In a pan, splutter mustard followed by cumin in hot oil. Add the curry leaves and red chilly pieces. Now add the shallots and green chillies. When the onion turns slightly brownish, add the sliced tomatoes.
When this turns mushy, add the Sambhar powder and hing, stir well. To this, add the cooked Daal and water for the gravy. Leave it to boil for a few minutes and add salt if required.
Garnish with fresh coriander leaves/cilantro.
As said before, Tiffin Sambhar is of very thin consistency, so add water. If you plan to add vegetables like potatoes or carrots, cook the pieces along with the Daal.
Since this is full of proteins and nutritious, it is ideal to add this to kids' breakfast.