Preheat oven to 180C

Heat oil in a frying pan, add the fish portions for a minute on both sides. Remove from the pan and set aside.

Add in all the vegetables and season generously with sumac, salt and pepper. Sautè until nearly soft, about 10 minutes.

Pour half of the vegetables into a casserole dish, layer the fish on top, followed by the rest of the vegetables.

Bake uncovered for 20-30minutes.