Wash potatoes thoroughly and cook in boiling water for about 20 minutes. In the meantime clean, wash and drain the spinach. Peel onion and garlic and dice finely. Wash the fish, dab dry and sprinkle with lemon juice. Season with salt and pepper.
Drain the potatoes, rinse and peel. Cut the potatoes into slices. Heat oil in a large pot, fry onions until translucent, add garlic and fry briefly. Add spinach and fry covered for 4-5 minutes. Season with salt and pepper. Meanwhile melt 40 g fat in a pot, dust with flour, sweat on and gradually deglaze with stock, cream and wine, stirring constantly. Bring to the boil while stirring and season to taste with salt, pepper and sugar. Finely crumble the bread. Mix crumbs and remaining fat with a fork. Mix potatoes and spinach, fill into a greased ovenproof dish.
Bring to the boil while stirring and season to taste with salt, pepper and sugar. Finely crumble the bread. Mix crumbs and remaining fat with a fork. Mix potatoes and spinach, fill into a greased ovenproof dish. Put salmon slices into it, press them in lightly and sprinkle with crumbs. Bake in the preheated oven (electric: 200 °C/ gas: level 3) for about 30 minutes. Serve garnished with dill and lemon wedges as desired