Heat oil in a pan. Once the oil is hot, add in asafetida and panchforan seeds.
Let the seeds crackle. Now add chopped onion, ginger, garlic, chili, and curry leaves.
Mix well and let it cook till the mix turns golden brown.
Now add turmeric powder, coriander seeds powder, and salt. Mix for few seconds.
Add in tomatoes, mix well and cover. Let it cook on low heat till tomatoes are mashed.
Now add peeled and cut rarbi. Mix well and cover. Let it cook for 2-3 mins till the masala coats well onto the arbi.
Close the heat. Garnish with chopped coriander leaves.
Serve with Chapati or steamed rice. Enjoy!