To begin, heat the vegetable oil in a large, heavy bottomed pot or Dutch oven over medium-high heat. Add the beef cubes in batches to avoid overcrowding, browning them on all sides. This step enhances the depth of flavour. Remove the beef and set it aside.

In the same pot, reduce the heat to medium and sauté the onions until they are golden and softened, about 5 minutes. Add the minced garlic and cook for another minute, stirring constantly to avoid burning. Deglaze the pot by pouring a small amount of the stock and scraping up the browned bits for added flavour.

Return the browned beef to the pot, along with the sliced smoked sausage. Stir in the marjoram, black pepper, and bay leaves. Mix well to coat the meat with the aromatic spices and distribute the flavours evenly.

Add the cubed potatoes, sliced carrots, and green beans to the pot. Pour in the remaining stock, ensuring the ingredients are fully submerged. Bring the mixture to a gentle boil, then reduce the heat to low. Cover and simmer for 45 minutes, stirring occasionally to prevent sticking.

After 45 minutes, add the sliced leek to the stew. Stir well and continue cooking for an additional 15 minutes, allowing the flavours to meld and the vegetables to become tender.

Taste the stew and adjust the seasoning as needed, adding salt gradually. Keep in mind that the smoked sausage may contribute to the saltiness, so taste before adding more.

Once the vegetables and meat are fully tender and the flavours have melded, remove the bay leaves from the pot. Let the stew rest off the heat for 5 minutes to allow the flavours to settle and the temperature to slightly cool.

Serve the Eintopf hot in large bowls, garnished with freshly chopped parsley for a burst of colour and freshness. Pair it with crusty bread or rolls to soak up the flavourful broth. For an authentic touch, serve alongside a crisp German pilsner or a refreshing glass of apple cider.