3 cups of rice, 1 cup of urad dal (split black gram), 1 teaspoon fenugreek seeds, salt to taste, water for grinding and soaking, 1/4 cup of cooked rice (optional).
Soak the rice (both regular and parboiled) in a large bowl with enough water to cover it for 6-8 hours or overnight. Soak the urad dal and fenugreek seeds together in another bowl for the same duration.
Drain the water from the soaked rice and urad dal. Grind the urad dal and fenugreek seeds first. Grind the rice next. Add the soaked rice (and cooked rice if using that) to the grinder with some water. Transfer all to the same mixing bowl.
Mix both batters thoroughly. Add salt to taste and mix well. Cover the bowl and let it sit in a warm place for 8-12 hours or overnight until it doubles in volume and has a slightly sour aroma.
Dilute the batter slightly with water to achieve consistency in the pancake batter. Heat an appam pan and pour a ladleful of batter into the centre. Swirl the pan to spread the batter thinly around the edges with a thicker centre. Cover and cook on medium heat.
Adjust the consistency of the batter if needed, making it slightly thinner than the pancake batter. Heat the tawa. Pour a ladleful of batter into the centre and spread it in a circular motion. Drizzle some oil around the edges. Cook until the dosa turns golden brown.
Keep the batter slightly thicker than the dosa batter. Pour a ladleful of batter onto the hot griddle and spread it slightly. Top with finely chopped vegetables like onions, tomatoes, green chillies, and coriander leaves. Cook on medium heat.