Prepare the ingredients.
Soak the dried shrimp in the hot water for about 1-2 minutes. Drain all the water and set the shrimps aside.
Slice the shallots and red bird's eye chillies thinly and set aside.
Peel the mango skin with a peeler. With the knife in your dominant hand, make deep cuts into the mango, while slowly turning the mango around with the other hand. Then, bring the knife parallel to the mango, and slice off chunky strips while using your finger to guide the blade. Carefully rotate the mango as you do so, until all the depth of the deep cuts have been reached. Repeat this step until there is no more flesh left, and do it all over again for the next mango.
Gather all the mango strips into a mixing bowl, and set aside in the fridge to chill.
Heat the cooking oil in a wok over medium heat.
Marinate the fish fillets with salt, spreading them evenly.
Break and whisk an egg, then pour half of it over the fillets. Coat the fish evenly with the egg.
Sprinkle 30g of the crispy flour over the fish and coat it generously. If it's still a little wet, add about 10g more of the flour and mix until combined.
Test the cooking oil by dipping wooden cooking chopsticks. When bubbles form at the tip, the oil is ready for deep frying.
Add the fish fillets one by one. Separate any fillets that are stuck to each other. Deep fry them for about 8 minutes, or until golden brown. Flip and rotate them every 2-3 minutes for them to be even in colour.
Remove with a strainer, shaking off excess oil, and rest on a cooling rack.
Remove the mango strips from the fridge. Add salt, sugar, chilli, shallots, dried shrimp, fish sauce and roasted peanuts. With a gloves hand, toss to mix the ingredients together, squeezing the mango slightly ever so often.
Taste and adjust.
Plate both the fish fillets and mango salad on a serving plate. Garnish with roasted peanuts and chopped spring onions, and serve.