01 - Heat a large skillet over medium-high heat. Sear beef cubes in batches until browned on all sides. Transfer browned beef to the slow cooker.
02 - Add onions, garlic, carrots, bell peppers, and potatoes to the slow cooker with the beef.
03 - Stir in diced tomatoes with juices, beef broth, paprika, caraway seeds, marjoram, bay leaf, salt, black pepper, and tomato paste. Mix thoroughly to combine all ingredients.
04 - Cover and cook on low setting for 7-8 hours or on high for 4-5 hours, until beef and vegetables are very tender.
05 - For thicker consistency, mix cornstarch with cold water to create a slurry. Stir into slow cooker 30 minutes before serving. Cook on high, uncovered, until thickened.
06 - Remove bay leaf and taste for seasoning adjustments. Serve hot, garnished with chopped parsley and a dollop of sour cream if desired. Enjoy alone or with crusty bread or egg noodles.