Soak the peanuts for 3 to 4 hours in drinking water. They will soften and increase in size.
Pressure cook the peanuts with water and salt for 3 to 4 whistles.
Make the Peanut Masala
In a kadai, pour the oil and heat it. When hot, crackle the mustard seeds and then the whole cumin seeds.
Add the chopped ginger and garlic and saute till the raw smell reduces. Add the curry leaves and mix well.
Add in the chopped onions and green chillies. Fry till soft and light golden brown in color.
Put in the chopped tomatoes and add salt to taste. Add the turmeric powder, chilli powder, cumin powder and coriander powder. Mix well and cook till the tomatoes are mushy.
Add garam masala and the boiled peanuts. Mix well to combine. Add a little water and cook till a thick masala is formed. Check the salt and add more if needed. Top with fresh coriander leaves as a garnish and serve hot.