Blanching asparagus is a simple way to cook it for eating, but it’s also a method used to pre-cook it before using other methods, or when adding it into other dishes. You don’t necessarily need to blanch it before every cooking method, but when cooking it at a high temperature (like grilling or searing) for a shorter period, you might end up with asparagus that seems done on the outside, but overall is still tough/undercooked.