Wash the meat, dab dry and cut into cubes of about 3 cm. Peel and roughly dice the onion. Clean, wash and cut the leek into rings. Clean, wash and halve the mushrooms. Wash, quarter, core and cut apples into slices.
Heat the oil in a frying pan. Sauté the meat in it vigorously while turning. Season with salt and pepper. Take out. Fry onion, leek, mushrooms and apples in hot frying fat for about 5 minutes. Add meat again. Dust everything with flour and sauté briefly. Deglaze with cider and 1⁄4 l water. Wash the marjoram, shake dry and add to the meat. Bring everything to the boil, cover and braise for about 30 minutes.
Cook the pasta in plenty of boiling salted water according to the instructions on the packet. Approx. 10 minutes before the end of the braising time, stir mustard into the goulash. Season to taste with salt and pepper. Serve everything.