Wash 1 cup of masoor dal thoroughly and soak it in water for 30 minutes. Drain the water and set aside.
In a pressure cooker, add the soaked masoor dal, 3 cups of water, 1/2 teaspoon turmeric powder, and 1 teaspoon salt. Cook for 3-4 whistles on medium heat. Once the pressure releases, open the cooker and check if the dal is cooked. If not, cook for another whistle.
In a separate pan, heat 2 tablespoons of ghee or oil. Add 1 teaspoon cumin seeds and let them crackle.
Add 1 finely chopped onion and sauté until it turns golden brown.
Add 1 teaspoon ginger-garlic paste and sauté for a minute.
Add 2 finely chopped tomatoes and cook until they turn soft and mushy.
Add 1/2 teaspoon red chili powder, 1/2 teaspoon coriander powder, and 1/4 teaspoon garam masala. Cook for 2-3 minutes until the spices are well-blended.
Pour the cooked masoor dal into the pan with the tadka (tempering) and mix well. Adjust the consistency by adding water if required. Cook for 5-7 minutes on low heat.
Garnish with chopped coriander leaves and serve hot with rice or roti.