Bring a large pot of salted water to boil. Add the cabbage leaves and cook until tender, about 4-5 minutes. Drain the leaves into a colander in the sink and run them under cold water. Set them aside.

Heat the butter in a small skillet over medium heat. Add onion and garlic and cook, stirring, until soft, about 7 minutes. Stir in the paprika and allspice and cook, stirring, until fragrant, about 2 minutes.

In a large bowl, mix the beef, rice, sour cream, 2 teaspoons salt, and the onion mixture until well combined. Season with pepper to taste.

Lay the cabbage leaves on a work surface and blot dry with paper towels. Split the thick part of the cabbage leaves, if necessary, to create a level filling surface. Place about 1/2 cup of the beef mixture in the bottom center of each leaf. Roll the bottom of a leaf over the beef mixture, fold in the sides of the leaf around it, and continue rolling forward until completely closed. Repeat with the remaining leaves. Arrange the rolls seam side down in a 10x13 baking dish.

Preheat the oven to 375°.

Make the tomato sauce: In a medium saucepan, combine the tomatoes, broth, bay leaf, and salt. Bring to a boil and season with pepper to taste. Pour over the cabbage rolls and cover the baking dish tightly with foil. Bake for 1 hour.

Remove the foil from the baking dish and continue cooking, basting occasionally until lightly browned and cooked through, about 20-30 minutes more. Serve in the baking dish.