Combine split Pigeon peas (Arhahr dal), Mung dal-lentils, and Red lentils(Masoor dal). Rinse the lentils 2 to 3 times until the impurity clears. Soak lentils with enough water to cover for 15 minutes.
Add soaked lentils, water, turmeric powder, cumin-coriander powder and salt to an InstantPot or a Pressure Cooker. Pressure cook in an Instant Pot on high setting for 15 minutes with natural steam release.
For pressure cooker cooking, cook on high heat until 2 whistles. Turn the heat down to low and cook for 8-10 minutes. Natural Pressure release.
Whisk dal with a whisk or use a hand blender(if needed) until smooth.
Heat oil in a wok or a sauce pan on medium heat. Add cumin seeds. Once the oil starts to become cloudy around cumin seeds, add minced onions. Cook onions until slightly golden.
Now add minced ginger and garlic, sauté for a few seconds. Add diced tomatoes, whole chilis, dried fenugreek, Kashmiri chili powder, and curry leaves. Cook on low-medium while stirring for about a minute or until tomatoes start to break apart.
Add tadka to cooked Dal. If Dal is too thick add ½ cup of hot water to thin it down. Boil the Dal to reduce the liquid if needed. Garnish it with chopped cilantro and Garam Masala.