Cut the meat into approx. 2 cm cubes. Peel and roughly dice the onions.
Heat the oil in a large saucepan and fry the meat on high heat until light brown, season with salt and pepper. Add the onions and fry for 2 to 3 minutes. Pour in the juice and stock and cover and simmer over medium heat for about 45 minutes.
In the meantime, peel the potatoes and pumpkin, cut into large pieces, add to the meat together with the thyme and cook for another 15 to 20 minutes.
Roast the pumpkin seeds in a pan without fat. Quarter, core and cut the apple into small cubes; Mix with lemon juice and pumpkin seeds.
Season the stew with salt and pepper and serve sprinkled with the apple and pumpkin seed mixture.