Add salt to the boiling water, then drop the potatoes in and boil for 6 minutes. As they boil, scrape and/or peel the carrot, then cut it lengthwise in quarters, and then crosswise in thirds. Cut the green beans to be approximately the same lengths as the carrots. At the 6 minute mark, add the carrots to the boiling water. After another 3 minutes, add the green beans for 2 minutes. Drain the vegetables; potatoes do not need to be completely done, but you should be able to stab them with a fork and stay on the fork without crumbling. Refresh with cold water.