Masala dosa is a crispy South Indian crepe filled with spiced potato filling, served with sambhar and chutney. This popular vegetarian breakfast is a family favorite that's both satisfying and relatively healthy.
Soak urad dal and rice separately in water for at least 6 hours or overnight, then drain and blend each to a smooth batter using minimal water. Combine, mix well, and ferment the batter in a warm place for 8–12 hours until bubbly.
Peel and roughly mash the boiled potatoes. Slice the onion thinly and finely chop the green chilies. Set aside along with curry leaves.
Heat 2 tbsp vegetable oil in a skillet over medium heat. Add mustard seeds and let them splutter, then add curry leaves, onions, and green chilies, sautéing until onions are translucent.
Stir in the turmeric and add the mashed potatoes and salt. Mix thoroughly over medium-low heat until everything is heated through and aromatic. Set this spiced potato mixture aside.
To cook each dosa, heat a large nonstick skillet or griddle over medium-high, brush lightly with oil, pour 1/2 cup batter in the center, and quickly spread it outward in a thin circle with the back of a ladle.
Drizzle a little oil along the edge, cook until the underside is golden and crisp (about 2–3 minutes), then place a portion of the potato filling in the center and fold the dosa over. Serve hot with chutney and sambhar.