Rinse the whole fish thoroughly under cold running water, clean both inside and out. Pat the fish dry with paper towels to eliminate moisture, which helps prevent splattering during frying.

Make shallow diagonal cuts on both sides of the fish, about 2-3 inches apart to aid in cooking and flavor absorption.

Generously dust the entire fish with cornflour, coating both sides evenly and shaking off excess flour.

In a deep pan, pour in vegetable oil to a depth of about 1-2 inches and heat over medium heat to around 350°F.

Carefully lower the fish into the hot oil, cooking for approximately 8 minutes on one side until golden brown, then flip and fry for another 8 minutes.

Remove the fish from the oil once crispy and golden, placing it on paper towels or a wire rack to drain excess oil.

In a mortar and pestle, crush the garlic and chilies until achieving a coarse paste.

Combine cornstarch with a splash of water in a small bowl and whisk until smooth, setting aside for later use.

Heat oil in a saucepan over medium heat and sauté the crushed garlic and chilies until fragrant and golden.

Stir in palm sugar, tamarind paste, fish sauce, and water into the sautéed mixture, simmering until the sugar dissolves.

Pour in the reserved cornstarch mixture and stir until sauce thickens, achieving a glossy texture.

Serve the fried fish on a platter, drenching it generously with the tamarind sauce and garnishing with herbs if desired.