Trim the green bean stems and cut in half. Wash and drain in a colander and set aside.
Heat olive oil in a large skillet over medium heat. Add the onions and sauté until translucent. Stir in the garlic, tomatoes, sugar salt, pepper and bring to the boil.
Add the green beans, tossing so that the green beans are thoroughly coated with the olive oil and the tomatoes. Turn heat to simmer, cover with the lid and cook for 30-35 minutes, until the beans are soft and most of the juices have evaporated.
Stir in the chopped parsley. Serve warm or at room temperature with crumbled feta cheese and kalamata olives.