Rinse the whole fish under cold water to remove any impurities, then pat it dry thoroughly with paper towels. Make shallow diagonal cuts into the flesh about 1 inch apart to allow for even frying.

Evenly coat the prepared fish with cornflour, ensuring all surfaces are covered. Gently press the cornflour into the fish skin and flesh to promote adherence and achieve a crispy texture when frying. Allow the coated fish to rest for a few minutes while you heat the oil.

In a deep pan or heavy-bottomed skillet, pour in enough neutral oil to submerge half the fish and heat it over medium heat. Use a thermometer to check that the oil reaches about 350°F (175°C) before adding the fish.

Carefully lower the coated fish into the hot oil, ensuring you do so away from you to avoid splatter. Fry the fish for about 8 minutes on one side, or until it appears golden brown and crispy. Flip the fish and fry the other side for an additional 8 minutes until evenly crispy.

Once the fish is perfectly fried, use a large spatula to carefully lift it from the oil and transfer it to a plate lined with paper towels. This helps drain excess oil.

While the fish is draining, crush the chilies and garlic together, creating a fragrant base for the tamarind sauce.

In a small bowl, prepare a cornstarch slurry by mixing 1 tablespoon of cornflour with 2 tablespoons of water until smooth. This slurry will help thicken the tamarind sauce.

In a saucepan, heat a tablespoon of oil over medium heat and add the crushed garlic and chilies. Sauté them for about 1-2 minutes until fragrant.

Add the palm sugar, tamarind paste, fish sauce, and 2 teaspoons of water into the saucepan with sautéed garlic and chilies. Stir continuously until the palm sugar fully dissolves and all ingredients are well-combined.

Incorporate the prepared cornstarch slurry into the saucepan, stirring continuously until the tamarind sauce becomes glossy and slightly thickened, about 2 minutes.

On a large serving platter, arrange the crispy fried fish and generously drizzle it with the warm tamarind sauce. Garnish with extra chilies or fresh herbs like cilantro.