Trim all excess fat from round steak. Cut into 8 evenly shaped pieces. Pound steak pieces between waxed paper until very thin and easy to roll. In skillet, lightly brown sausage. Drain well and combine with parsley, 1/2 teaspoon oregano, garlic, onion, and salt; mix well. Spread each steak with 2 to 3 tablespoons of sausage mixture. Roll up steaks and tie. Stack steak rolls in crockpot.
Combine tomatoes, tomato paste, salt, and 1 teaspoon oregano; pour over rolls. Cover and cook on low setting for 8 to 10 hours. Serve steak rolls with sauce.
SAUCE: Place all ingredients except flour, oil, and vinegar in crockpot; stir well. Cover and cook on low setting for 8 to 10 hours. Remove cover and turn to high setting for the last hour to reduce excess moisture. Before removing sauce from crock pot, stir in flour, oil, and vinegar. Allow to cool. Pour 3 cups of sauce at a time into blender container; blend until smooth.