For the Tom Yum Broth, fill a medium saucepan with 750ml water. To the saucepan of water, add half of the chillies and half of the galangal. Add the lemongrass, shallot, palm sugar, fish sauce and tamarind, then cover and bring to the boil. Once boiling, reduce heat and simmer for 5 minutes.
Remove from the heat and strain through a sieve lined with muslin cloth into a clean saucepan. Return to the stove over a low heat, then add in the remaining chillies and galangal. Remove from the heat and add the kaffir lime leaves, juice and zest. Season with salt, to taste, then set aside with lid on to keep hot.
For the Crispy Shallots, spread the sliced shallots onto a plate and pat dry with paper towel.
Place the rice bran oil into a wok over high heat. Add a slice of shallot to the oil to test whether it is hot enough for frying. Once hot, add the shallots to the oil and fry until golden and crisp. Remove from the oil and drain on paper towel. Season with salt and set aside until needed.
For the Grilled Barramundi, rub the lemongrass over the barramundi and season with salt. Place the barramundi fillets onto a plate and cover with cling film. Set aside in fridge to marinate for 20 minutes.
Remove from the fridge and drizzle fillets with 1 tablespoon of the grapeseed oil.
Add fillets, flesh side down, to the preheated barbeque or grill and cook until approximately ¾ cooked through, about 2-3 minutes. Remove from the heat and set aside, keeping warm.
Lightly brush the barramundi skins with the remaining ½ tablespoon of grapeseed oil. Season and place the skins onto the charcoal grill and cook until crisp, about 2 minutes. Remove from the heat and drain on paper towel. Season with salt and set aside until needed.
To serve, place the saucepan of Tom Yum Broth over a low heat and bring to a simmer.
To serve, reheat broth to a simmer. Position the Grilled Barramundi in the centre of each serving bowl. Lift out the chillies from the broth and place a few on each plate. Top with some Crispy Shallots and a piece of Crispy Skin. Add a few sprigs of Thai basil leaves to the plate. Transfer the hot Tom Yum Broth to a serving jug and serve on the side.