First, heat a skillet over medium heat. Add 2 tablespoons oil, then add 1/2 teaspoon mustard seeds. When the mustard seeds start to pop, add the urad dal, chopped green chilies, garlic, ginger, and curry leaves. Sauté for a short time.

Add the chopped onion. Add salt and turmeric, and sauté the onion for 2-3 minutes. Then add the chopped tomato.

Cook until the tomato softens. Add the boiled potatoes, mashed. Mix well.

After mixing, add 1-2 tablespoons water and cook for 2 minutes. The potato masala is ready.

To make the dosa batter, combine 1 1/2 cups rice, 1/2 cup urad dal, 2-3 tablespoons chana dal, and 1/2 teaspoon fenugreek seeds in a bowl. Wash and soak for 8 hours.

Soak for at least 6-8 hours until the rice and dal are well soaked. Add some of the soaked rice and dal to a grinder jar along with 1/2 cup poha (for crispier dosas) and some water. Grind to a slightly coarse batter. Grind the remaining rice and dal the same way; do not make it too fine.

Let the ground batter ferment for 12-16 hours. In warm weather, it ferments faster; in cooler weather, it takes longer. Once well fermented, add 1/2 teaspoon salt and mix.

Heat a nonstick or cast iron griddle. Pour 1 large ladleful of batter onto the griddle. Spread it into a round dosa shape. Drizzle a little oil or butter around the edges.

When the dosa turns golden on the bottom, spread some potato masala filling on top. Roll up the dosa. Your aloo masala dosa is ready. Serve hot with sambar, coconut chutney, or tomato chutney.