Wash and dry asparagus. Break off woody end by holding the end and about half way down the asparagus, then bend and snap it at the natural point it breaks. Place on a tray or plate.
In a small bowl, whisk together vinegar, lemon zest, lemon juice, mustard, onion powder, salt, and pepper. Slowly whisk in the olive oil to emulsify the marinade.
Drizzle 2 Tablespoons marinade over the asparagus and toss to coat (add a little more if it’s not coated).
Place asparagus perpendicular to the grate (so it won’t fall through). Grill the asparagus directly over medium heat for about 6-8 minutes until tender, turning once or twice, leaving the grill closed otherwise.
Sprinkle with salt and remaining marinade and serve.
Notes
Hold asparagus at each end and snap off where it naturally breaks. This will remove the toughest portion of the asparagus.
For evenly sized asparagus, use the first one as a guide and cut the remaining to match.
Avoid asparagus falling through the grill grates by placing them perpendicular to the grates.
Asparagus cooks quickly, so be careful not to over cook or burn them.
Refrigerate leftovers in a covered container for up to 3 days.