Heat Oil in a Cheenachatti and add mustard seeds and black gram dhal into the hot oil. When the mustard seeds splutter, add chopped ginger and green chilli and stir it.
Then add chopped onion, curry leaves and green peas and stir it well.
When colour of the onion and green peas turns into golden brown color, add red chilli powder, turmeric powder and salt. After about 2 – 3 minutes, add the grated beetroot also and stir the mix properly. Cook the beetroot well.
Add cooked and smashed potato into this mix and stir it further. Masala for the dosa is ready.
Heat Dosakkal (Dosa making Stone) and apply some Oil on the stone and pour the dosa batter and spread the batter in round shape.
When dosa batter is cooked, apply some more oil or ghee on the dosa and about one big spoon Masala (which is already prepared and kept separately) and spread it on the Dosa.
After one or two minutes, fold the dosa and take it out from the Dosakkal and keep in a serving plate. The delicious masala dosa is ready. Serve with coconut chutney and sambar as accompaniment.