Initial Infusion: Gently toss the fish chunks with the garlic paste, turmeric, salt, and asafoetida. Let the fish rest for 15–20 minutes to absorb the flavors and neutralize odors.
Prepare the Dry Rub: While the fish marinates, toast the whole cumin, coriander, and carom seeds on a low flame. Once cooled, grind them with the mango powder, black salt, and ginger powder into a fine dust.
Make the Batter: In a separate bowl, whisk chickpea flour, cornstarch, and chili powder. Gradually add garlic water until you have a thick, paste-like consistency.
Double Coat: Pour the chickpea paste over the marinated fish. Toss until each piece has a paper-thin, even coating. It should look like a spiced film, not a thick batter.
The First Fry: Heat oil to 330°F (165°C). Fry the fish in small batches for 3–4 minutes until the coating sets and the fish is nearly cooked through. Drain on a wire rack.
The Rest: Allow the fish to rest for 5–10 minutes. This allows the internal moisture to settle, preventing a soggy crust.
The Flash Fry: Increase the oil temperature to 365°F (185°C). Flash-fry the rested fish for just 60 seconds until it reaches a shatter-crisp texture and a deep golden color.
The Final Touch: Remove the fish and immediately toss with a generous dusting of your homemade Signature Spice Powder. Serve hot with lemon wedges and mint chutney.