Clean, wash, quarter and cut the savoy cabbage into strips. Blanch in boiling salted water for about 2 minutes. Drain well
Peel and finely chop the onion. Wash the salmon, dab dry, cut into pieces
Heat 50 g fat in a pot. Sauté onion in it until transparent. Dust with flour and sauté briefly. Stir in milk, cream and stock. Bring to the boil and simmer for about 5 minutes. Season to taste with salt, pepper and lemon juice
Put some sauce in a greased large casserole dish. First put 3 lasagne plates, some sauce, half savoy cabbage and again 3 lasagne plates. Spread some sauce on top. Season salmon with salt and pepper and place it on top. Spread 3 lasagne dishes, some sauce and the rest of the savoy cabbage on top. Finish with the remaining lasagne and sauce.
Sprinkle cheese over it. Bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2) for approx. 40 minutes. Garnish with chervil
Drink: cool white wine