Slice the vegetables lengthwise and keep aside. Potatoes, Plantain and elephant yam should be placed in a vessel with water. Else it will oxidize with oxygen and turn black.
Pressure cook carrot, beans, white pumpkin with little water and salt.
Before cooking potatoes and elephant yam, replace the water and pressure cook it. Add enough water to pressure cook it.
Don't pressure cook the sweet pumpkin. Cook it directly in a vessel, else it will be over cooked. But I cooked everything in a pressure cooker.
Meanwhile extract tamarind juice.
Grind the coconut and chillies into a fine paste and keep it aside.
Once the vegetables are cooked, add tamarind extract and boil for 5 min. So that it will blend with the vegetables.
At this stage add coconut oil, curd, curry leaves. Also add the ground coconut paste.
Donot cook aviyal after adding the curd and coconut paste.
Add more coconut oil inorder to increase the flavour and the delicious aviyal is ready to serve.