In a heavy bottom pan add oil and add the mustard seeds, and let is splatter.
Now add in the turmeric powder, hing or Asafoetida and let it roast for few seconds.
Now add the slit or chopped green chilies and curry leaves to the oil and let this also roast for few seconds.
Then add the orange peal and the orange pulp and cook for a 5 minute or so.
At this point add in the sambar power and salt and give it nice stir and cook it for another 2-4 minutes.
Add in the tamarind paste and about 1- 1/2 cup of water ( adjust to the sourness of the tamarin also add the jaggery.
Let this mixture cook and boil till the mixture reduces to a good gravy consistency.
If you are using the soaked, and squeezed tamarind water make sure to let it boil till the raw smell is completely gone.
Add the curry leaves in the end and turn off the heat.
Orange flavored vathalkizhambu is ready to be served with some Hot rice.