Rava dosa with turmeric potatoes

For the filling, put the potato chunks in a large saucepan of salted water and bring to the boil. Cook for 15-20 minutes oruntil tender. Drain well; set aside to cool.

Meanwhile, put the semolina, flours and salt in a large mixing bowl. Add the yogurt, if using, and 600ml water; whisk well until smooth. Stir in the chilli, ginger, pepper, cumin, coriander and onion. Finally, whisk in 360ml water. Rest for 20 minutes to allow the semolina to absorb the water.

While the batter is resting, return to the filling: heat the oil in a frying pan over a medium heat. Add the mustard seeds and cook until they start to crackle. Stir in the split peas, chillies, ginger and curry leaves. Cook for 1-2 minutes until fragrant, then add the onions. Reduce the heat to low and cook for 8-10 minutes until softened. Stir in the turmeric for the final 2 minutes. Roughly crush the cooled potatoes with a fork and stir into the spiced onion mixture in the pan. Cook for 5 minutes to heat through, then remove the curry leaves. Cover and keep warm.

Whisk the batter again; it should have a thin, watery consistency. Heat a nonstick or cast-iron frying pan (about 24cm in diameter) until it starts to smoke. Reduce the heat to low-medium and pour a ladleful of the batter into the middle of the pan. Use the back of the ladle to quickly spread the batter evenly over the base of the pan to form a thin pancake. Drizzle 1 tsp oil over the dosa, then cook until crisp and golden underneath and bubbly on top (about 5 minutes). Transfer to a baking tray and keep warm. Repeat until the remaining batter is used up. (You should have enough to make 10.) Stuff the dosas with the turmeric potatoes and roll up, then serve with chutney and pickled onion on the side.