Ingredients

• 400 g raw short-grain rice such as sona masoori or idli rice
• 130 g whole skinned urad dal
• 1 tsp fenugreek seeds
• 2 tbsp thick poha
• 350 ml cold water
• 1½ tsp salt
• 600 g potatoes
• 3 tbsp vegetable oil
• 1 tsp black mustard seeds
• 1 tsp urad dal
• 1 tsp chana dal
• 1 pinch asafoetida
• 2 sprigs fresh curry leaves
• 2 onions
• 2 green chillies
• 10 g fresh ginger
• ½ tsp ground turmeric
• 120 ml water
• to taste salt
• 2 tbsp fresh coriander leaves
• 4 tbsp vegetable oil
• 1 small onion

Method

1. 01
   Soak rice and dal Rinse the rice three times and soak it with the poha in plenty of water. In a separate bowl, rinse the urad dal and soak it with the fenugreek seeds. Leave both to soak for about six hours.
2. 02
   Grind the urad dal Drain the urad dal and fenugreek and grind them with a little cold water at a time until the batter is smooth, thick and fluffy, then scrape it into a large bowl.
3. 03
   Grind the rice Drain the rice and poha and grind them with water into a smooth but very slightly gritty batter, about the texture of fine semolina, then add it to the urad dal batter.
4. 04
   Mix and ferment Add the salt and mix the two batters together well with your clean hand for a minute, then cover the bowl loosely and leave it in a warm place for about ten hours until it has risen and smells pleasantly sour.
5. 05
   Boil the potatoes Boil the potatoes in salted water until a knife slides in easily, about twenty minutes.
6. 06
   Peel and crumble potatoes Drain the potatoes, let them cool enough to handle, then peel them and crumble them coarsely with your hands, leaving some small chunks.
7. 07
   Temper the spices Heat three tablespoons of oil in a wide pan over medium heat, add the mustard seeds, and when they pop add the urad dal, chana dal and asafoetida and fry until the dals turn golden, about one minute.
8. 08
   Soften the onions Add the curry leaves, sliced onions, green chillies and ginger, and cook, stirring, until the onions are soft and translucent but not browned, about five minutes.
9. 09
   Finish the filling Stir in the turmeric, then add the crumbled potatoes, the water and salt to taste, and simmer gently for about three minutes until the mixture is soft and just holds together. Stir in the coriander leaves and turn off the heat.
10. 10
    Prepare the batter Gently stir the fermented batter without beating out the air, adding a few spoonfuls of water if needed so it flows like thick pouring cream.
11. 11
    Heat the tawa Heat a cast iron tawa or flat griddle over medium high heat for about three minutes, then rub the surface with the cut side of the half onion dipped in a little oil.
12. 12
    Spread the dosa Pour a ladle of batter into the centre of the pan and immediately spread it outward in a spiral with the back of the ladle to make a thin round crepe.
13. 13
    Crisp the dosa Drizzle about one teaspoon of oil around the edges and over the top, and cook until the underside is golden brown and crisp and the edges lift away from the pan, about two minutes.
14. 14
    Fill and fold Place two to three tablespoons of the potato filling in the centre, fold or roll the dosa over it, and serve right away with coconut chutney and sambar. Wipe the pan with the onion again before making the next dosa.