In a suitable soup kettle, place the meat, bay leaf, whole onion, tomato, celery rib cut in half, and the salt. Cover with cold water and bring to a rapid boil. Skim several times. Lower heat and cook until meat is tender (approximately 1 hour). Allow meat to cool in stock, then remove to platter and shred. Strain stock and reserve to be used in sauce and the rest for a hearty soup. Tomato Sauce For Ropa Vieja: Heat oil in large skillet. Add onion and green pepper and saute until transparent. Add the garlic, bay leaf, oregano, cumin, and cook 5 minutes longer. Combine tomato sauce, sugar, vinegar, stock, salt, and wine. Add to saute. Stir to mix well and bring to a boil. Lower heat and cook for approximately 30 minutes, stirring at intervals. In a 2-1/2 quart casserole with cover, place the shredded meat. Pour sauce over the meat and mix well. Cover and simmer for another 20 to 30 minutes, stirring occasionally. Serve over white rice accompanied by very ripe fried plantains, when available.