In a large heavy skillet cook onion, garlic, celery, ;arrot, and scallion in butter over moderate heat, stiring, 5 minutes. Cook vegetables, covered? stirring lccasianally. until carrot is tender, about 5 minutes nore. Stir in salt, pepper. Worcffstershire sauce, and 1 cup of ketchup and cook, stirring. 1 minute.