For potato masala, In a pan, add oil, mustard seeds, urad dal, chana dal, curry leaves, 2 chopped green chilli, 1 tsp ginger paste, 1 medium size onion slice, turmeric powder and boiled and mashed potatoes. Mix well.
Switch off the gas; add lemon juice and coriander leaves. mix well. The potato stuffing is ready.
Now heat, tawa and grease it with oil. Spread uttapam batter with ladle.
Spread potato stuffing on uttapam and press it slightly.
Sprinkle some onion, tomatoes and coriander leaves on uttapam stuffing.
Apply some butter on the top of the masala and the sides of uttapam.
When the lower sides become crisp, flip uttapam and cook it on another side. Cook it for 2 minutes.
Serve masala uttapam with coconut chutney.