Boil the drumsticks in a small utensil by adding 2 cups water. Keep it aside.
Wash the toor dal and keep aside for 30 minutes.
Take the pressure cooker pan and heat it. Add onion, tomato and toor dal along with 2 cups water and pressure cook for 4 to 5 whistles or till dal is cooked. Switch off the gas and wait till pressure from cooker is released on its own.
Heat a kadai and add oil. After it gets heated add mustard seeds.
After mustard seeds flutter, add cumin seeds, asafeotida, dry red chillies and curry leaves and fry for few 2 minutes.
Add chopped garlic and sauté till raw smell of garlic goes away.
Add turmeric powder and red chilli powder and mix well.
Add boiled dal from the pressure cooker and mix.
Also take the boiled drumsticks and add them to the cooked dal and simmer for 5 minutes on low heat.
Add salt to taste.
Garnish with chopped coriander leaves. Serve hot.