Trim the woody bottom third from each asparagus spear—snap it where it naturally breaks. This removes the part nobody wants to eat anyway. I used to feel wasteful until I realized I was just tossing bitterness.
Pat asparagus completely dry with paper towels. Moisture prevents the char you're after. Wet vegetables steam instead of sear, which defeats the whole purpose of grilling anything at all.
Combine olive oil, minced garlic, lemon zest, and lemon juice in a small bowl. Whisk it together—this mixture needs to coat every single spear evenly because the garlic and lemon are doing the heavy lifting flavor-wise.
Toss dry asparagus with the oil mixture until every spear gets coated. This takes about thirty seconds, not complicated. I find using my hands works faster than a bowl and spoon.
Arrange spears perpendicular to grill grates, running left to right. Heat your grill to medium-high, around 400 degrees Fahrenheit. Place asparagus directly on hot grates and close the lid. Don't touch it yet—let the char develop.
After five to six minutes, carefully rotate each spear a quarter turn using tongs. You should see dark golden marks where the grate touched the spear. This is exactly what you want.
Cook another four to five minutes until the asparagus bends slightly when you pick up a spear with tongs. The exterior should look slightly charred, not burnt. Tom tested this by bending a spear—it should flex but not be floppy.
Remove asparagus to a serving platter and immediately sprinkle with kosher salt, black pepper, Parmesan, toasted sesame seeds, and fresh parsley while still hot. The heat helps everything stick. Serve immediately while the char is still happening inside your mouth.