Soak the brown chickpeas in cold water overnight. Drain, rinse and set aside.
Press the sauté button, add the oil and allow it to heat up for a minute. Once the oil is hot, add the mustard seeds to the pot. Once the mustard seeds begin to splutter, add the onions and stir-fry for 10-12 minutes, or until the onions begin to brown.
Add the Serrano pepper, curry leaves, garlic, ginger and spices and stir-fry for 30 seconds, then add the tomatoes and cook for 5 minutes, or until they begin to break down.
Add the brown chickpeas and water. Mix well.
Secure the lid, close the pressure valve and cook for 30 minutes at high pressure.
Naturally release pressure.
Add coconut milk and press sauté to cook for 3-4 minutes.