Clean and wash 500 grams of fish fillets (preferably boneless) and pat them dry with a clean cloth or paper towel.
In a mixing bowl, combine 1 teaspoon ginger-garlic paste, 1 teaspoon red chili powder, 1/2 teaspoon turmeric powder, 1 teaspoon coriander powder, 1/2 teaspoon garam masala, salt to taste, and 2 tablespoons of lemon juice. Mix well to form a smooth paste.
Apply the spice paste evenly on the fish fillets, ensuring they are well coated. Marinate the fish for at least 30 minutes.
In a separate bowl, mix 1/2 cup of gram flour (besan), 1/4 cup of rice flour, a pinch of baking soda, and salt to taste. Gradually add water to form a thick batter.
Heat oil in a deep frying pan or kadai over medium heat. Dip each marinated fish fillet in the batter, ensuring it is well coated.
Carefully slide the coated fish fillets into the hot oil and deep-fry them until they turn golden brown and crispy. Flip occasionally to ensure even cooking.
Remove the fried fish from the oil using a slotted spoon and place them on a paper towel to absorb excess oil.
Serve hot with mint chutney or ketchup and a side of lemon wedges.