Preheat the oven to 400°F. Trim the ends of the green beans and place on baking sheet. Toss beans with olive oil and spread out evenly on baking sheet. Roast for 8 minutes, then add pecans and shallots and continue roasting another 5 minutes or until beans are lightly browned and crisp tender. Remove from oven, sprinkle with oregano and black pepper before serving.