Combine 2 cups hot water and the tomato paste in a 6-quart slow cooker. Add the crushed tomatoes, red pepper flakes, sugar and basil and stir to combine. Cover and cook on high while you prepare the meat.
Butterfly the steak: Slice in half horizontally, leaving 1 long side attached so you can open the steak like a book. Place between 2 pieces of plastic wrap and pound until about 1/4 inch thick. Remove the plastic; season the steak with salt and pepper. Scatter the provolone evenly over the steak, then top with the garlic, breadcrumbs, pecorino, raisins, pine nuts and parsley.
Starting with a long side, tightly roll up the steak like a jelly roll. Secure with twine in several spots. Transfer to the slow cooker; reduce the heat to low, cover and cook 7 hours.
Remove the meat to a cutting board and let rest 5 minutes. Remove the twine, then slice 1 inch thick. Serve with polenta; top with more sauce from the slow cooker.