Open the butterflied steak and, with waxed paper covering it, pound evenly with a meat mallet until approximately 1/4 inch thick. Rub the lemon rind, salt, pepper, and 1-1/2 teaspoons oregano into the meat.
Lay the prosciutto slices evenly on the steak. Sprinkle the bread crumbs, grated Parmesan, & parsley evenly over the prosciutto slices. Roll the braciole tightly, taking care while rolling to tuck in both ends so as to hold in the filling while cooking. Tie the roll with strings at 1-1/2 to 2 inches intervals.
Rub the rosemary between your palms to break it up. Season the flour with the rosemary, remaining oregano, and salt and pepper. Rub this mixture onto the surface of the beef roll.
In a pan large enough to hold the roll, heat the olive oil over moderately high heat. Add the beef roll, turning to brown the entire surface.
Add the garlic and onion and cook until the garlic begins to turn golden brown. Add the wine and cook for one minute.
Add the tomatoes with their juice and salt & pepper to taste. Cover the pan and simmer over low heat for 1 to 1-1/2 hours or until very tender when pierced with a fork. If liquid appears to be diminishing during the cooking, splash a bit more wine into the pan.
Remove from pan & place on a heated platter. Remove the strings, cut into 1/2 inches thick slices, pour the tomato mixture over the slices and serve.
Note: If serving cold, place the braciole on a platter, pour the sauce over it, cover tightly with plastic wrap or foil, and refrigerate. Before serving, bring to room temperature, remove the strings, and cut into slices as mentioned previously. The slices can be served on a bed of lettuce, accompanied by freshly baked bread.