Wash the fish, dab dry and cut into large pieces. Sprinkle with lemon juice and season with salt and pepper. Place the fish in a casserole dish. Peel and chop the onions. Drain the cucumbers.
Dice ham and gherkins. Heat the fat and fry the onions. Add ham and gherkins. Stir in sour cream, mustard and starch one after the other. Season to taste with Madeira, salt, pepper and sugar. Spread the mixture over the fish. Sprinkle with Gouda. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 30 minutes. Serve garnished with lemon slices and salad.
Season to taste with Madeira, salt, pepper and sugar. Spread the mixture over the fish. Sprinkle with Gouda. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 30 minutes. Serve garnished with lemon slices and salad. Boiled potatoes taste good with it