In a saucepan, with a lid, over medium heat, add the oil. When the oil is hot, add the onions, celery, and green peppers. Season with salt and pepper. Saute the vegetables for 2 to 3 minutes or until the vegetables start to wilt. Stir in the garlic, tomatoes, and herbs. Continue to saute for 1 minute. Season the vegetables with salt, pepper and cayenne. Stir in the Worcestershire sauce and stock. Bring the liquid to a boil and reduce to a simmer. Cook for 12 minutes, covered, stirring occasionally. Stir in the green onions and stir in the butter. Serve warm.