Rinse fish fillet with cold water, dry and cut into 4×4 cm pieces. Place on a plate, sprinkle with salt and turmeric and sprinkle with juice of one lemon. Leave to marinate for about 10 minutes.
Mix chickpea flour, chili seasoning and ajwain in a baking bowl.
Squeeze and add garlic, add egg and whisk all together until a smooth batter is formed. Heat oil in a high saucepan. Dip the fish pieces in the batter and then remove them with a fork, place them in the hot oil. Fry both sides in oil for about 4-5 min, degrease on kitchen roll. Sprinkle chat masala on top and garnish with lemon slices.