Sear the Beef: Pat the beef cubes dry with paper towels. Season generously with salt and pepper. Heat the lard or oil in a large, heavy-bottomed Dutch oven over medium-high heat. Sear the beef in batches, ensuring not to overcrowd the pot, until deeply browned on all sides. Remove the beef and set aside.

Caramelize the Onions: Add the sliced onions to the Dutch oven and cook over medium heat, stirring frequently, until they are deeply golden brown and caramelized, about 20-25 minutes.

Bloom the Spices: Stir in the sweet paprika, smoked paprika, caraway seeds, and marjoram into the onions. Cook for 1-2 minutes, stirring constantly, until fragrant.

Deglaze and Combine: Stir in the tomato paste and cook for 1 minute. Deglaze the pot with the red wine vinegar, scraping up any browned bits from the bottom. Add the beef broth and bay leaves. Return the browned beef to the pot.

Simmer Low and Slow: Bring the mixture to a simmer, then reduce the heat to low, cover the Dutch oven, and simmer for at least 3 hours, or until the beef is incredibly tender. Stir occasionally to prevent sticking.

Thicken (Optional): If desired, add the cubed potato during the last hour of cooking. You can also add the sliced red bell pepper at this stage for added sweetness.

Adjust Seasoning: Remove the bay leaves. Taste and adjust seasoning with salt and pepper as needed.

Serve: Serve hot, garnished with a dollop of sour cream or crème fraîche and a sprinkle of fresh parsley. Excellent served with buttered noodles, spaetzle, or crusty bread.