To prepare, place potatoes in a large saucepan; add water to cover, and bring to a boil. Cover and cook 10 minutes. Add green beans, and cook 5-7 minutes or until beans and potatoes are tender. Drain well, slice potatoes.
In a large skillet, heat oil over medium-high heat, until hot. Add garlic, cook 1 minute, stirring often. Add tomato, oregano and salt; bring to a boil. Reduce heat, and simmer 5 minutes. Stir in potato and beans, and cook until vegetables are thoroughly heated.