Soak the rice in a bowl of water for 6 hours. At the same time, soak the lentils and fenugreek seeds inanother bowl of water for 6 hours.
Drain the rice, then transfer to a blender or food processor and process, gradually adding 125ml / 4 1/2fl oz (1/2 cup) water to make a fine batter. Transfer to la clean bowl.
Drain the lentils and fenugreek seeds, transfer to a blender or food processor and process, gradually adding 3 tablespoons of water to make a fine batter.
Combine the rice and lentil batters and season with salt. Set aside to ferment for 8 hours.
Mix the ginger, chilies, curry leaves, coriander leaves and cumin seeds into the batter, then stir in a little water, if necessary, to make a thick batterof pouring consistency.
Heat a tawa, flat griddle or frying pan (skillet) over high heat until it sizzles when a few drops of water are sprinkled on to it. Reduce the heat and smear a very thin film of oil evenly over the tawa.
Pour a ladleful of batter into the centre of Tawa and spread it out quickly using a circular motion with the back of the ladle to form a 15cm / 6 inch round dosa.
Drizzle 1 teaspoon oil around the edges, then increase the heat and cook for about 2 minutes, or until the base is golden brown. Turn the dosa carefully and fry for a further 2 minutes, or until golden brown.
Remove from the pan and serve hot. Make the others the same way.