Heat a kadai with the oil.
Add the garlic and chillies and saute till garlic browns.
Now, add the onions and saute till it turns pink.
At this stage, add the tomatoes and saute till oil seperates.
Add the tamarind to this and saute for a min.
Let the mixture cool.
Once cool, add the coriander leaves and salt.
Blend to a smooth paste in a blender.
Temper with mustard seeds, hing and curry leaves.