In a bowl mix together the oil, lemon juice, salt, black pepper and chopped coriander. Pour the marinade over the fish fillet and allow marinating. Wrap the fish fillet in aluminum oil and steam for 8-10 minutes.
In a separate pan add the chopped onion and chopped green chilies. Fry for 2-3 minutes until the onions are tender. Add the boiled peas, chopped red capsicum, salt and black pepper powder. Cook until the vegetables are tender. Turn the flame off.
Peel the orange and scoop out the flesh. Serve the steamed fish with the fried vegetables and top with the oranges.