Spread the onions in the bottom of an 8-cup slow cooker. Toss the beef with the flour, 1 teaspoon salt and 1/4 teaspoon pepper and place on top of the onions. Top with the bell peppers and garlic. Stir together the broth, paprika, tomato paste and caraway and pour over the beef. Cover and cook until the meat is very tender, either on high for 4 to 5 hours or on low for 7 to 8 hours.
Uncover and let stand at least 10 minutes. Stir in the sour cream and dill and season to taste with salt and pepper. Serve over egg noodles or potatoes.