Remove the stalky ends of the asparagus by snapping or trimming the last 1 – 1 1/2 inches of each stalk. If using larger or thicker stalks of asparagus, peel the outer layer with a vegetable peeler. Transfer asparagus to a small casserole dish. 

In a small saucepan, combine shallots, sherry vinegar, Dijon mustard, kosher salt, black pepper, sugar, and canola oil. Bring to a boil and carefully pour over asparagus.

Submerge asparagus in vinaigrette and cover with plastic wrap. Allow asparagus to marinate at least 20 minutes or up to overnight. Store in refrigerator. Serve either chilled or at room temperature.