Wash the potatoes and cook for about 20 minutes. Quench, peel and cut into slices. Peel and finely chop the onion. Sort spinach, wash and blanch briefly in boiling salted water. Drain (defrost frozen spinach). Seasoning
Heat the fat. Sauté the onion in it. Dust with flour and sweat. Deglaze with 350 ml water while stirring. Stir in cream and stock. Add wine if necessary. Simmer briefly. Season to taste with salt, pepper and sugar
Salmon wash, dab. Cut into pieces. Sprinkle with lemon and season. Place in a greased casserole dish with potatoes and spinach. Pour sauce over it. Bake in a hot oven (electric cooker: 200 °C / convection oven: 175 °C / gas: level 3) for 25-30 minutes