Submerge 1 cup rice in a bowl of water. In a second bowl, cover 4 tablespoon moong dal and the soaking spices in water. Leave both to soak for 6 hours.
Drain the soaked rice and transfer it to a blender. Process until completely smooth, trickling in 125 ml water as needed, then scrape into a clean mixing bowl.
Drain the dal and fenugreek seeds, then blend them with 3 tbsp water until fine and creamy. Stir this lentil paste into the ground rice along with salt to taste. Cover and leave to ferment for 8 hours.
Stir 4.8 g ginger, 18–24 g green chilli, 1 g curry leaf, 1–2 g coriander leaf, and the batter spices into the fermented mixture. If needed, thin with a splash of water to achieve a thick, pourable consistency.
Set a flat griddle or frying pan over high heat until a few flicked droplets of water immediately sizzle and evaporate. Turn down the heat and wipe the surface with a bare film of vegetable oil.
Pour a ladle of batter onto the middle of the pan and quickly swirl outward with the bottom of the ladle to produce a 15 cm (6 inch) circle. Trickle 1 tsp vegetable oil around the circumference, increase the heat, and fry for roughly 2 minutes until the underside is deep golden.
Gently flip the pancake and fry the second side for another 2 minutes until browned. Transfer to a plate, keep warm, and cook the remaining dosas in the same manner.
Use equal weight. It cooks in about the same time and breaks down to a similar soft, creamy consistency, though the colour will be slightly pinkish-orange.