Clean and wash the fish pieces. Sprinkle salt, turmeric and red chilli powder and coat the fish pieces well. Leave aside for 30 minutes.
Finely chop the onions, coriander leaves, slit the chillies lengthwise; wash and pick curry leaves.
Heat oil in a deep-bottomed or a non-stick kadai. Fry the fish pieces till brown on both sides; remove and keep aside.
Add a tablespoon of oil to the same pan. Add curry leaves and green chillies. Sauté.
Add chopped onions (or onion paste) and fry till brown. Add ginger-garlic paste and fry for 1-2 minutes. Add turmeric, chilli powder, garam masala and salt to taste and fry for a few seconds.
Slide in the fried fish pieces, mix gently and fry until the fish pieces are well coated with the masalas.
Garnish with coriander leaves.
Remove and serve Chepala Vepudu Andhra style with onion rings and lemon wedges.