Wash the lemon and grate dry. Peel 1/3 of the lemon peel with a zest ripper. Rinse fish fillet, dab dry and season with salt and pepper. Spread a piece of aluminium foil thinly with oil, place the fish fillet on top and sprinkle with lemon peel. Close aluminium foil tightly over the fish fillet
Wash and clean the tomato and cut into small cubes. Wash and clean spring onions. Cut the white part into small cubes, the green part into thin rings. Heat the rest of the oil in a pot, fry the diced spring onions and 3/4 of the rings in it. Add the diced tomatoes, bay leaf and thyme and bring to the boil, simmer for 3 minutes. Slice the olives and drain the capers.
Add both to the sauce and cook for another 5 minutes. Put fish parcels in a pot with little water, cover and cook for about 5 minutes. Take out and open the packet. Season the sauce with salt, pepper and sugar, remove the bay leaf boeatt. Put the sauce on a plate. Arrange the fish on top, garnish with caper apples and the remaining onion green