Wash okra. Cut off any hard stems and dry okra thoroughly. Heat oil in large saucepan and fry onions with the halved garlic cloves until slightly soft, transparent, and golden. Add okra and continue to fry until slightly softened. Add the sliced tomatoes and saute for a few min. longer. Season to taste with salt and pepper. Cover with water, bring to a boil and simmer until the okra is very tender, usually about 1 hour. Squeeze in the lemon juice and cook for a further 15 min. (If using canned okra, cooking time will be much shorter. Serve hot or cold. If to be served cold, allow to cool in the saucepan before turning out into a serving dish. Recipe from "A Book of Middle Eastern Food" by Claudia Roden. Alfred A. Knopf, 1972.