Sauté chillies, onion, and garlic in oil for 7 minutes, then blend until smooth and cool.
Boil sweet potato with orange juice, sugar, 200ml water, and spices until tender.
Drain sweet potato, rinse under cold water, and discard the whole spices.
Infuse ginger, garlic, and coriander in lime juice for 3 minutes then strain.
Mix the strained juice with salt and the prepared chilli paste.
Soak red onion in iced water for 5 minutes, drain, and dry thoroughly.
Toss fish with salt for 2 minutes to open pores.
Pour tiger's milk over fish and let it marinate for 2 minutes.
Gently fold in onions, coriander, chilli, and sweet potato before serving immediately.