Place a pressure cooker on the stove and add oil. When the oil turns hot, add mustard seeds and chana dal; splutter
Add curry leaves and green chillies; sauté
Furthermore, add onion; sauté till onion turns translucent
Add kashmiri chilli powder, turmeric powder and salt; sauté for a minute
Add tomato and bring to a slight boil
Mix once and make sure no spice powder is stuck to the cooker
Add coriander leaves, close the cooker and cook for 10 minutes (6-7 whistles). Once steam releases naturally, open the cooker lid and mix well
Add besan flour and mix well, and cook for 5 minutes till the thokku comes together
Finally, add coriander leaves and turn off