Stir together lemon juice, zest, thyme, garlic paste, pepper, salt, and red chilli powder. The lemon and thyme sharpen the flavour, while the spices anchor it. Mix until the paste looks smooth and the aromatics are evenly spread.

Add the fish pieces to the marinade and coat all sides well. Resting the fish for this duration helps it absorb flavour without breaking down or turning mushy. Cover the bowl and refrigerate for about 20 minutes. Take the fish out of the fridge just before you start coating and frying.

Combine semolina and rice flour on a wide plate. Semolina gives the crust its bite, while the rice flour lightens the texture so it doesn’t feel dense. Spread the mixture evenly so the coating goes on smoothly later.

Beat the egg until fluid and airy. Dip each marinated fish piece into the egg, lift it slightly to drain excess, then press it firmly into the semolina mix. Coat both sides without leaving bare patches. Set the coated pieces aside for five minutes so the crust holds better during frying.

Pour oil into a pan, just enough to form a shallow layer. Warm it on medium heat until it reaches around 170–175°C. You can test by dropping a tiny pinch of semolina; it should sizzle gently instead of burning or sinking.

Place the pieces in the hot oil with a little space between them. Let each side fry for 3–4 minutes until the crust turns deep golden and crisp. Avoid flipping repeatedly; a single flip keeps the crust intact and prevents the fish from drying out.

Lift the fried pieces onto absorbent paper to remove excess oil. Serve immediately while the crust is firm and crackly.