What does it mean to shock a green vegetable?
A green vegetable is shocked after blanching by throwing it into an ice bath (cold water with ice cubes added) to stop the cooking process.
This ensures that your broccoli, broccoli raab, spinach or green beans will stay crisp and also keeps them bright green. As soon as your shocked vegetables have cooled, remove them from the bath so they don't absorb excess water and let them dry off or place them on a kitchen towel to absorb excess moisture.
The term "refresh" is also used as a synonym for this process, but shocking is a more accurate term.