Season the beef cubes generously with ground sea salt and freshly ground black pepper; set aside.
In a Dutch oven over medium-high heat, add oil and when hot, working in batches, add beef cubes. Sauté the meat until browned on all sides, about 3 to 4 minutes.
Transfer the cubes to a bowl using a slotted spoon and set aside while working with the remaining cubes.
Reduce the heat to medium and add butter.
When it starts sizzling, add onions, carrots and celery; season generously with ground sea salt. Cook until almost soft, about 4 minutes, scraping the bottom of the pot to dislodge any brown bits.
Add garlic, cumin, coriander, and sugar; sauté for 30 seconds. Add tomato paste and stir to coat.
Return the meat and add beets, cabbage, beef, vegetable broth, and bay leaves. Stir well, increase the heat and bring the mixture to a soft boil.
Reduce the heat back to medium and simmer for 45 minutes.
30 minutes later, add paprika and vinegar; stir well. Continue cooking for the remaining 15 minutes.
Portion the soup into bowls, top with sour cream and garnish with dill. Serve with crusty bread.