Wash the red and yellow lentils, drain. Combine in a saucepan with water over medium heat. Cook for 18 to 20 minutes or until yellow lentils are tender. Reduce heat to low and simmer.
Meanwhile make the tempering(spiced oil)
Heat oil in a skillet over medium heat. when the oil is hot, add the cumin seeds and mustard seeds. Let them start to sizzle and pop. The cumin seeds should darken in color and get fragrant, mustard seeds will lighten and start to sizzle and pop. Add asafetida, green chili, onion, garlic, ginger and a pinch of salt. Cook until the onions turn translucent, about 5 -7 minutes. Stir occasionally. Add splashes of water in between to cook evenly.
Add coriander/ garam masala , turmeric, and cayenne and mix well. Add tomatoes, lemon juice and a splash of water and mix. Cook until the tomatoes are saucy. Mash the larger pieces. About 6 minutes.
Add the cooked lentils to the skillet. Add salt and half of the chopped cilantro, and continue to simmer the soup for 3 to 4 minutes, or until bubbling. Taste and adjust salt and spice. Add a dash of lemon juice if needed.
Garnish with cilantro and serve hot with rice or flatbread with a side of roasted veggies or Indian spiced vegetable side.
Video
Notes
For variation: Add 1/2 to 1 cup coconut milk instead of water.Instant Pot: Cook the lentils in an Instant Pot with 1.5 to 2 cups water for 3 minutes at high pressure with a 5 minute quick release. Add the tempering from the skillet and simmer on sauté mode for 2 minutes. Garnish and serve.This recipe is naturally soy-free and nut-free. Omit the asafetida for gluten-free.