Wash the meat, pat dry, place on the fat pan of the oven and bake in the preheated oven (electric oven: 175 °C/ gas: level 2) for approx. 1 hour. In the meantime, clean and wash the spinach and let it drain well on a sieve.
Wash potatoes thoroughly and cook in boiling salted water for about 20 minutes. Cook spinach in little boiling salted water for about 5 minutes, pour on a sieve and drain well. Roast the pine nuts in a dry pan and take them out.
Drain the potatoes, rinse and peel them. Heat 2 tablespoons of oil in a frying pan, fry the potatoes for 8-10 minutes, turning them until golden brown and season with coloured pepper. In the meantime, peel and chop the onions.
Wash and quarter the tomatoes. Heat the remaining oil in a pot, fry the onions in it until transparent, add spinach, fry for about 5 minutes while turning and season with salt and pepper. Fold in tomatoes.
Serve the meat, vegetables and potatoes on a plate sprinkled with pine nuts and garnished with marjoram if desired.