Heat ⅓ cup oil in a pan.
Add 1 tsp cumin seeds, 1 tsp mustard seeds, and ½ tsp nigella seeds. Let them splutter.
Add 4 chopped onions and sauté until translucent.
Add 2 cubed potatoes and cook for 3-4 minutes.
Stir in 3 blended tomatoes.
Add red chilli powder, coriander powder, turmeric, salt, and crushed red chillies. Cook until the oil begins to separate.
Add 1 kg tinday and mix well to coat with the masala.
Cover and cook on low heat for about 30 minutes, stirring occasionally, until the tinday and potatoes are tender.
Garnish with green chillies, fresh coriander leaves, and a light sprinkle of mustard and nigella seeds.