Boil water and cook pasta as indicated on the package. Drain and let it cool.
Chop the green beans and cook them in boiling water with a little salt until they are tender.
Chop the onion in big pieces and the garlic in really small pieces. In a frying pan, heat the oil and margarine, add the onion and the garlic and cook for about 2 minutes; then, add the green beans and fry for another 2 minutes.
When the green beans are soft, add the soy sauce (about 1 tablespoon), the salt, pepper and pasta. Fry for another minute and serve warm. You could have this delicious pasta as a side dish or as a main dish with fresh salad.