Peel and wash shallots. Cut crosswise 3 mm thick.
150 g shallots
Wash green and red chillies. Cut diagonally 4 mm thick.
1 red chilli, 1 green chilli
Wash tomato. Cut into bite-size wedges.
150 g tomato wedges
Stir sugar with light soya sauce, dark soya sauce and vinegar till dissolved.
5 tsp sugar, 3 tbsp light soya sauce, ½ tsp dark soya sauce, 3 tbsp Chinese white rice vinegar
Wash fish and dry with paper towels. Sprinkle evenly with salt.
500 g pomfret (2 small fish), ¼ tsp salt
Pan-fry fish in hot oil over medium-high heat till golden brown. Transfer to a plate.
5 tbsp vegetable oil
Remove oil from wok, leaving about 2½ tbsp. Stir-fry shallots till light brown. Add chillies and tomato. Stir-fry till soft.
Return fried fish to pan/wok. Drizzle with half of soya sauce mixture. Let fish sizzle for a few seconds. Flip. Repeat drizzling and sizzling. Add water and bring to a boil.
300 ml water
Reduce heat to medium-low. Simmer gently, drizzling top of fish with the sauce from time to time, till fish is saturated and flavourful, about 3 minutes.
Taste and adjust seasoning if necessary. Sauce should be full-bodied, mildly sour and subtly sweet. Serve hot or at room temperature with plain rice or porridge.