Mix lemon juice and turmeric to a paste. Spread this all over and inside the fish and set aside.
Heat oil in a pan.Add in curry leaves, onions and cook till golden.
Add in ginger garlic paste, chillies and cook for a min,
Add in all the spice powders and mix well.
Add in tomatoes, salt and cook till the tomatoes turns mushy.
Add in coriander leaves and mint leaves. Mix well. Masala done..
Now line a foil, spoon some masala in the bottom. Lay the fish in, spoon some masala into the fish and over the fish. Lay tomato slices over this. Cover and bake this for 30 to 35 mins.