Spread roast open; pound to 1-inch thickness with a meat mallet.
Sprinkle salt and pepper over entire surface of roast; rub with 1 tablespoon olive oil.
Sauté 1/2 cup onion, garlic, and hot sauce in 1/4 cup olive oil in a large skillet until onion is tender. Add mushrooms and ham; cook 5 minutes. Remove from heat. Add breadcrumbs and milk; mix well.
Place stuffing mixture on roast, leaving a 1/2-inch margin. Roll up jellyroll fashion, enclosing the stuffing completely. Tie securely with string. Sprinkle roast with marjoram, thyme, and 1 teaspoon flour.
Place in a well-greased shallow roasting pan. Insert meat thermometer, if desired. Bake at 500° for 25 minutes or until roast is browned.
Combine broth, wine, 1/2 cup onion, celery, green pepper, and bay leaves, mixing well. Reduce heat to 375°. Pour gravy mixture over roast, and bake 45 minutes or until meat thermometer registers 170° (well done), basting occasionally. Transfer roast to a serving platter; remove string. Let stand 10 minutes before slicing. Reserve pan drippings
Combine 3 tablespoons flour and a small amount of water to form a smooth paste. Stir into pan drippings. Cook over medium heat, stirring constantly, until thickened and bubbly. Remove bay leaves; discard. Slice roast, and serve with gravy. Garnish with lemon slices.