Add a few inches of water to a steamer (or large pot with a steamer insert) and bring to a boil. While water is heating, trim the ends of the green beans, and cut carrots into sticks about the same thickness as the beans. When water starts to boil and steam, add the carrots and steam for 3 minutes. Then add green beans and steam for 4-5 minutes more, or until all the vegetables are tender-crisp.