Wrap the coated fish cubes in banana leaves. Tie with thread.
Place the wrapped packets in a single layer in a 10" quiche dish. Micro, covered, for 8 mins. on High, turning once. Let stand covered for 5 mins.
Serve wrapped in banana leaves.
For tamarind paste: Combine 400 gms. tamarind with 1.25 cups hot water and Micro uncovered for 6 mins. on High, stirring once after 4 mins. Remove and let stand covered for 5 mins. Mash to loosen the pulp and separate the seeds. Pass the tamarind pulp through a fine sieve.