Peel and chop the onions. Quarter the turnip, peel, wash and cut into relatively fine cubes. Dab meat dry. Heat 2 tablespoons of oil in a casserole dish. Sauté the meat in it, turning it well.
Add the onions and about half of the turnip and fry briefly. Season with salt, pepper and paprika.
Add tomato paste, stir in and briefly sweat. Deglaze with 1 litre water, bring to the boil. Cover and stew at low to medium heat for about 1 1/2 hours.
In the meantime peel, wash and cut the potatoes into pieces. Cook potatoes and remaining turnip in boiling salted water for about 25 minutes.
Drain the potato mixture, allow to steam briefly. Bring milk and 6 tablespoons of oil to the boil. Coarsely mash the potato and vegetable mixture with a potato masher. Let the milk and oil mixture run in. Season to taste with salt and nutmeg.
Stir starch and approx. 3 tbsp. water until smooth. Boil up the goulash and stir in the starch. Bring to the boil and simmer for about 1 minute, season with salt and pepper.
Put approx. 2/3 of the goulash in an ovenproof dish and spread the mashed potatoes on top. Add the rest of the goulash. Crumble the bread finely. Grate cheese coarsely, mix both with 2 tablespoons of oil. Sprinkle crumb mixture on the casserole.
Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for 20-25 minutes. Wash oregano, shake dry and pluck the leaves from the stalks. Remove the casserole from the oven and garnish with oregano.