Rinse the whole masoor thoroughly under running water. Soak them in enough water for at least 1 hour. Drain and set aside.
If using a pressure cooker, add enough water to cover the lentils completely along with 1/4 of chopped onion. Close the lid and cook for about 2-3 whistles or until the lentils are tender.
If using a pot, add about 2-3 cups of water and cook on medium-low heat for about 30-40 minutes or until the lentils are cooked through. Stir occasionally and add more water if needed.Once the lentils are cooked and the desired consistency is reached (slightly thick and creamy), turn off the heat.
In a dry pan, roast the coriander seeds, cloves, cinnamon stick, black peppercorns, shahjeera, and mace over low heat until fragrant. Allow them to cool.
(use garam masala or kitchen king masala if you dont have whole masala available)
Once cooled, grind the roasted spices into a fine powder using a spice grinder, combine ginger, garlic, soaked cashews, and chopped tomatoes. Blend into a smooth paste. Set aside.
Heat oil in a large pot Add bay leaves and slit green chili. Sauté for a minute until fragrant.
Add the finely chopped onion and cook until it turns golden.
Add the spice mixture-ginger-garlic-tomato-cashew paste to the pot. Cook for till the oil starts coming out. stirring occasionally.
Add salt to taste and red chili powder. Adjust the amount of chili powder according to your preference for spiciness.
Add cooked masoor and onion to the onion tomato gravy.
Add butter on top and Garnish with freshly chopped coriander leaves.
Serve the Akka Masoor hot with rice, roti, or naan.
Enjoy your flavorful Akka Masoor!