Season fish portions with salt and pepper. Heat oil in deep frying pan and fry fish for 5 minutes on each side, or until medium brown. Remove from oil and drain on paper towel.
Sauce: Heat oil in separate pan, add onions, vinegar, water, sugar and spices, and cook until well blended, 10–15 minutes. Add salt to taste. Place drained fish slices in a deep dish and cover with hot onion mixt