Bring the potatoes to the boil covered with water and cook for 20 minutes, drain, let cool and peel. Wash the eggplant, clean and cut into thin slices. Place the aubergine slices on kitchen paper and sprinkle with salt, leave to stand for about 15 minutes.
Peel off shallot and garlic, cut into small pieces. Heat 3 tablespoons of rapeseed oil in a pan and fry the minced meat until crumbly. Add shallots and garlic and sauté briefly. Add tomatoes (skinned from the tin) and tomato paste, stir in and bring to the boil Season with marjoram, cinnamon, salt and pepper.
Thoroughly dab the eggplant with kitchen paper in a pan with 2 tablespoons on both sides and place on kitchen paper. Cut the potatoes into thin slices and place about half of them in a baking dish (20 + 20 cm). Wash the tomatoes and remove the stalks. Cut two tomatoes into thin slices.
Place the minced meat, aubergines, tomatoes and finally the potato slices alternately on top.
For the bechamel sauce: melt the butter in a saucepan, stir in the flour and let it sweat briefly. Pour in the milk and stock, stirring constantly, bring to the boil and simmer over a mild heat for 10-15 minutes. Stir in the Gouda. Béchamel sauce - cheese - Spread the sauce on top. Preheat the oven to 200 degrees. Bake on the middle rack for about 30 minutes
For the cucumber and tomato salad: Wash the cucumber with the remaining tomatoes, finely grate about 3 pieces. Mix lemon juice, 3 tablespoons water, 3 tablespoons rapeseed oil, salt and pepper vigorously. Roughly chop parsley and mix in. Salad for about 10 minutes. Let it steep and serve with the moussaka.