First pressure cook dal along with turmeric pd. & salt, keep it aside.
In another vessel, boil all the vegetables along with onion, little curry leaves, ginger & 1 tsp coconut oil.
When the vegetables are half boiled, add the juice of tamrind and cook till the vegetables are done (don't over cook)
Now add the dal along with 3 tsp of sambar powder (you can get it from any Indian grocery store) little curry leaves & salt. let it simmer for few minutes.
Turn off the heat, add the chopped corriender, close the lid ,keep it aside.
Take a pan pour 2 tsp of coconut oil, add rai, red chillies, and curry leaves, pour it into sambar.