Cut eel crosswise in 3" sections, dry and roll in flour. Sprinkle with rosemary and fry in oil over medium heat until golden brown on both sides. Remove from heat and set aside. For the marinade, strain the oil after frying the eel. Combine the vinegar and water and boil for 2 min. Meanwhile, saute garlic and onion in the leftover oil. Add the vinegar and water, bay leaf, rosemary, salt and pepper to taste. Cook 5 min. over low flame, remove and let cool. In a deep serving dish place the eel and cover with the sauce and let marinate in the fridge for several hours before serving. Can be served over cold pasta and garnished with fresh chopped tomato and a sprig of rosemary.