I love this thokku to be bit spicy so I have added little more chilli powder but if you feel its too much then add according to your spice need.
You can take small gooseberry tamarind soak squeeze and add only needed juice of it depending upon the tanginess.
If you are using tangy tomatoes then no need to add tamarind at all.
Always use gingelly oil only no other oil will give the exact flavour.
For tempering add sufficient oil so that it can be kept at-least for a week in fridge.