Place the dried whitebait and water in a large saucepan and bring to the boil over high heat. Reduce the heat to low and simmer for 45 minutes or until reduced to 4 litres. Strain through a fine sieve over a large saucepan, discarding the dried whitebait. Set aside.
Place the dried chilli in a small saucepan of boiling water, boil for 1 minute, then set aside for 15 minutes. Drain, reserving the water, then roughly chop and remove the seeds.
Preheat the oven to 180˚C.
Wrap the shrimp paste in foil, place on a baking tray and roast for 15 minutes.
Blend the shallot, galangal, lemongrass, turmeric and fresh chilli in a food processor or blender until a paste forms, adding the reserved chilli soaking water if necessary to form a paste.
Add the belacan and soaked dried chilli and blend until a smooth paste forms.
Place the stock over medium heat, then add the torch ginger flowers, Vietnamese mint and rempah paste and stir well and bring to the boil over high heat.
Place the dried tamarind in a bowl, cover with water, then drain and add to the laksa. Add the sugar and season with salt to taste. Bring back to the boil, then reduce the heat to medium, cover and simmer for 30–45 minutes.
Meanwhile, steam the fish in a steamer basket over a saucepan of simmering water for 20–25 minutes or until cooked. Discard the skin and bones and flake the flesh into large pieces.
To serve, add the fish to the laksa. Cook the rice noodles in a large saucepan of boiling water until just tender. Drain and divide among bowls. Remove the torch ginger flowers from the laksa, then spoon the laksa broth and flaked fish over each serve of noodles. Mix the shrimp molasses with the hot water.
Sprinkle a small amount of each garnish over each bowl and drizzle a teaspoonful of the shrimp molasses over the top. Serve immediately.