Peel, wash and slice the potatoes. Peel and roughly dice the onions. Cut bacon into strips. Wash, clean and cut leek into pieces. Cook the leek in boiling salted water for about 5 minutes.
Heat 2 tablespoons of oil in two large coated pans. Spread the potatoes and bacon on the pans and fry them for about 10 minutes, turning them over. Remove the leek, rinse with cold water and drain well.
Clean and trim the mushrooms. If necessary, cut large side-pieces in half lengthwise. Pluck oyster mushrooms roughly. Take out potatoes and ham and keep warm. Put mushrooms, onion and leek into the pans and fry for 5-7 minutes, season with salt and pepper.
Meanwhile wash the parsley and dab dry. Put something aside for garnishing. Pluck the leaves from the stalks and chop them roughly. Add parsley and potatoes to the mushrooms and season with salt and pepper.
Garnish with parsley. Thickened cranberries and sour cream taste good with it.