Chop the onion and lemongrass to a fine mix. Set aside.
In a small bowl, mix the chilli sauce, tomato sauce and oyster sauce, and set aside until needed.You can also always add the sauces straight into the pan individually, if you don't like the idea of washing up another bowl!
Thinly slice the other half of the onion, the garlic and chillies.
½ large onion
Quarter the tomato.
2 medium cloves garlic
Mix the cornflour and the 2 Tbsp of water into a paste and set aside.
½ tsp cornflour, 2 Tbsp water
Thinly slice the spring onions and chop the coriander leaves that you will be using as garnish.
125 ml water, ½ tsp cornflour
Let's fry the Fish (you can use an Air Fryer, if you prefer)
Heat the oil in a large frying pan or wok on medium heat and fry the fish until crispy and done. About 3 minutes each side, depending on the thickness of your fish. Fillets will only need a couple of minutes each side. Flip your fish over carefully.If you are happy to multitask, get the sauce going while you are frying the fish. If not, wait until the fish is done. This way, you will also only need the one pan/wok.
250 ml vegetable oil, 2 whole sea bream
When the fish is done, take it out and place it on a kitchen paper lined plate to absorb all the excess oil. Keep warm.
Let's Cook the Sauce
Pour out all but about 2 tablespoons of the oil and place back on the stove with a medium heat.
Fry the chopped onion and lemongrass for 2 minutes.
Add the sliced garlic and chillies and fry for 1 minute more.
Add the tiga rasa sauce, that is, the chilli, tomato and oyster sauces, along with the water. Mix well.
2 Tbsp tomato ketchup, 2 Tbsp chilli sauce, 1 Tbsp oyster sauce, 125 ml water
Tear the lime leaves at the edges and drop them in, along with the onions and chopped tomatoes. Stir and bring to a simmer.
½ large onion, 3 Kaffir lime leaves, 1 medium tomato
Remember the cornflour paste? Stir it then pour it all onto the sauce and stir well. Leave to cook for 2 minutes to allow the sauce to thicken. Check the seasoning and add some salt of you need it. I don't use extra salt in this recipe, as the sauces we use are enough.Turn off the heat.
½ tsp cornflour, 125 ml water
Line a large plate with the lettuce leaves all around the edges.
Place the fish in the middle and pour the cooked sauce all over, fully covering the fish.
Top with the chopped spring onions and coriander leaves and serve immediately.