Wash the string beans in cool water thoroughly. Pat dry with a paper towel. Cut off the tips of the beans on a clean, dry chopping board. Pour 2 to 3 inches of water in a pot and let it boil. Place the steaming rack over the boiling water and lay the string beans on top, being careful not to let the string beans touch each other.
Let the string beans boil 3 to 5 minutes. They should be soft on the outside yet still firm on the inside. While the beans are still wet from the steam, sprinkle or roll the string beans in seasonings. Let cool.
Place the string beans in a freezer-safe zipper bag. Carefully squeeze out any air inside the bag. You can store steamed yellow string beans for up to 10 months in the freezer.
Add the frozen string beans directly to dishes when cooking or baking.