Cook thur dal in a pressure cooker for 4 whistles,let cool and mash well.
Clean and cut cucumber to medium size pieces. Take a vessel and put chopped cucumber, onions,green chillies and tomatoes. Add mirchi powder, haldi powder and salt. To it add 2 cups of water and boil the ingredients for 5 to 8 mins. until cucumber becomes tender. Add the cooked dal to it and cook for 5 mins. Stir in between. Remove from the flame and keep aside.
Heat 1 table spoon oil in a pan and add Rai,jeera and urad dal. When rai splutters add mashed garlic flakes and curry leaves. Fry until golden bown and add the thadka to the dal. Dosa kaya pappu is ready.........
As cucumber tastes a bit sour there is no need to add tamarind pulp.(it is optional). Dosakaya pappu is one of Andhrites favorite dishes. Try once even you like it. Tasty to have with Rice, rotis and chapatis.