Heat sufficient oil in a kadai. Place fish in a bowl, add salt, red chilli paste, lemon juice, ginger paste, garlic paste and mix well and marinate for 30-45 minutes.
Add carom seeds, vinegar, gram flour, refined flour, turmeric powder, red chilli powder, chaat masala, garam masala powder and mix with hand. Add a little water if necessary.
The fish pieces should be well coated but the masala should be thick. Gently slide in each fish pieces into hot oil and deep till deep golden. Drain on absorbent paper and sprinkle a little chaat masala over them.
To make the dip put eggless mayonnaise and coriander-mint chutney in a bowl and mix well. Pass the mixture through muslin cloth into another bowl. Serve fish hot with the dip.