Make incisions on both side of the pomfrets and place on a plate. Sprinkle salt, drizzle 1 tablespoon lemon juice and add ½ teaspoon chilli powder and turmeric powder and rub well on both sides. Set aside for 5-10 minutes.
Take yogurt in a bowl. Add ginger-garlic paste, remaining chilli powder, garam masala powder, chilli paste, salt and remaining lemon juice and mix well. Add 1 tablespoon oil and mix.
Add the marinated pomfrets and coat well with the marinade. Set aside to marinate for 25-30 minutes.
Heat some butter on a non-stick tawa. Place the marinated pomfrets and shallow-fry, turning sides, till the fish is cooked and evenly done on both sides.
Transfer on a serving platter. Garnish with coriander leaves and serve hot with lemon slices.