Instructions. Remove any visible dirt from the green onions. Dirt commonly collects near the roots of the plants, but may appear on the leaves as well. Peel off any discoloration on the leaves of the green onions. If any leaves have become slimy, remove these as well. Green onions should be firm if not crisp. Place green onions in a strainer and rinse them with cool water. Turn onions to make sure all sides are thoroughly rinsed. Lay out a layer of paper towels on a counter or table surface. When you are done rinsing green onions, lay them gently on the paper towels to dry.