This is a wondrous dish from southern Indonesia. You see the Indian influences right off the bat (turmeric) and the Southeast-Asian influences (galangal, kaffir lime leaves, basil, etc.) The New World shows up as chilis, of course.
Ideally this dish is cooked with a whole fish or fish segments with bones but let's get real. Just make it with a fillet. It's not the same and it does matter but not substantially so.
Pair it with the most basic rice you can make because the flavors in the dish are already overwhelming.
4 tbsp lime juice
2 shallots (chopped coarsely)
2 cloves garlic
1 red chili
1/2" ginger (chopped coarsely)
1/2" galangal (chopped coarsely)
1 fresh turmeric (chopped coarsely)
lemongrass (sliced diagonally)
1" pandanus leaf
4 kaffir lime leaves
lemon basil (or Thai basil or Italian basil)
Note 1: Once you combine the lime juice with the fish, the clock is ticking. Do it after you make the paste, and right before you start cooking.
Make the tamarind water. Pour boiling water over the tamarind and let it steep for 20 minutes. Pass the mixture through a sieve keeping the water and discarding the residue.
Pound the shallots, garlic, chili, ginger, galangal, and turmeric to a paste. Set aside.
Combine the fish gently with the lime juice and tamarind water set aside. Let it sit for 10 minutes.
Heat up some peanut oil till it shimmers. Add the paste, lemongrass, pandanus, kaffir lime leaves and let it fry till the raw smell disappears. Add the water and bring to a boil. Let it cook for 5 minutes.
Add the fish and the lime juice and tamarind water. Let it cook through. This is swift. No more than a few minutes.
Top with the basil and serve at once.