Rinse and peel off the tough bottom of asparagus spears.
Place in a damp paper towel and “steam” in the microwave for about a minute and a half- you want them slightly cooked but still firm to the bite. Place in the refrigerator to chill while assembling salad.
Place barley, corn, butter beans, and scallions in a bowl.
In a separate bowl, whisk together the oil, vinegar, garlic and dry mustard. Add to the barley mixture along with the chilled asparagus and Parmesan cheese; mix well. Season with salt and pepper and serve with warm, crusty bread and butter, if desired.