Heat the oil in a frying pan. Brown the meat in batches for approx. 4 mins., remove from the pan, season.
Heat the oil in the same pan. Sauté the onion and garlic then add the tomatoes and continue cooking. Pour in the wine, return the meat to the pan, cover and simmer for approx. 5 mins. Stir in the marjoram.
Heat the butter in a pan. Add the flour and cook, stirring with a whisk; the flour must not take on any colour. Remove the pan from the heat. Pour in all of the milk at once and bring to the boil, stirring constantly, then reduce the heat, season, and simmer for approx. 10 mins., stirring occasionally, until the sauce is thick and creamy.
Put the meat sauce into the prepared dish, layer the aubergines and potatoes on top so that they overlap. Pour the béchamel sauce and crumble the feta over the top.
Approx. 35 mins. in the centre of an oven preheated to 200°C. Remove the moussaka and leave to stand for approx. 5 mins. before serving.