Pat 500g of fish fillets thoroughly dry with paper towels to ensure the marinade sticks properly. Cut into even, bite-sized portions.
In a small bowl, combine 1 tbsp lemon juice, 1 tbsp ginger-garlic paste, 1.5 tbsp Kashmiri chili powder, 0.5 tsp turmeric, 0.5 tsp garam masala, and 1 tsp salt to form a thick, uniform paste.
Rub the spice paste evenly over the fish pieces. Let it sit at room temperature for 15 minutes to allow the spices and salt to deeply penetrate.
Place 3 tbsp of semolina or rice flour on a shallow plate. Press each marinated piece of fish gently into the flour to coat both sides lightly, then shake off any excess.
Heat 3-4 tbsp of oil in a wide frying pan over medium-high heat. Once the oil shimmers, carefully place the fish in the pan. You should hear an immediate, active sizzle.
Fry undisturbed for 3-4 minutes until the bottom crust is firm and golden-brown. Gently flip and cook the other side for another 2-3 minutes. Drain on paper towels and serve hot.