marinate the fish pieces with some turmeric, salt and chili powder.
Fry those marinated fish pieces in some oil until golden brown, then take them out.
Now in the same oil add the vegetables and fry them until light brown. add some salt and the sliced onion and fry them again for 4-5 minutes in medium heat.
Once the onions soften, add garlic paste, turmeric and chili powder, salt and give it a mix.
Add the tomatoes and stir.
Add water and bring everything to a boil. Now cook everything in high heat for 10-15 minutes covered until the veggies are soft.
Add the fried fish to the curry, add fresh chilis, chopped coriander and, simmer for 5-7 minutes.
Simmer in low until you reach the desired sauce consistency.
Serve with a slice of lemon and steamed rice.