Peel and finely dice the onions. Clean and wash Brussels sprouts and cut larger ones in half. Clean, peel, halve and core the pumpkin and cut into 2 cm pieces. Peel and wash the potatoes and cut into 2 cm pieces. Melt the butter in a saucepan and sauté the onions until translucent. Add the potatoes and three stalks of thyme and sauté briefly. Pour in the vegetable stock and bring to the boil. Add Brussels sprouts and cook covered for 5 minutes. Add the pumpkin and cook for 15 minutes.
Cut the wiener sausages diagonally into 1 cm thick slices, mix into the stew and heat for 5 minutes. Season the stew with salt, pepper, nutmeg and a few squirts of lemon juice. Serve sprinkled with thyme leaves.