Heat oil in a pan and add the chopped garlic pieces. When it starts changing colour, add pottukadala. When garlic and pottu kadala is golden brown, add dried red chilli and fry for a min. Remove from fire and let it cool.
Grind the cooled roasted ingredients to a fine paste. Add coconut, tamarind, salt and water to this and grind again, till everything is mixed well.
Serve with Dosa, idly or Rice
Notes
The qty of tamarind depends on it's strength. Do a taste test first and add accordingly. Also be careful while adding salt, since tamarind may contain salt sometimes.