INSTRUCTIONS:
Heat the oven to 325°F with a rack in the lower-middle position.
Brown all the beef cubes in batches to prevent overcrowding. Get a light brown on all sides and them remove, set on a paper towel and set aside. Season the beef with 1 tablespoon of sweet paprika, 1 teaspoons salt and 1 teaspoon pepper; toss to coat. In a large measuring cup or small bowl, whisk together the broth and tomato paste; set aside.
In a large Dutch oven over medium, melt the butter. Add the onion and ½ teaspoon salt, then cook, stirring occasionally, until the onions are lightly browned, 8 to 10 minutes. Stir in the caraway and flour, then cook, stirring frequently, until the flour begins to brown, 2 to 4 minutes. Stir in the remaining 5 tablespoons sweet paprika and the hot paprika and cook until fragrant, about 30 seconds. Slowly whisk in the broth mixture and bring to a simmer, stirring frequently. Stir in the beef, bay and marjoram (if using), then bring to a simmer over medium-high. Cover, place in the oven and cook for 2 hours.
Remove the pot from the oven. Uncover and stir, then return to the oven uncovered and continue to cook until a skewer inserted into the meat meets no resistance, another 30 minutes, being careful not to overcook. Remove from the oven, stir and let stand, uncovered, at room temperature for 15 minutes. Stir in the dill and vinegar. Taste and season with salt and pepper. Ladle into bowls and garnish with dill sprigs. Serve with sour cream.