Rinse the asparagus and trim off the woody ends. To do this, you can simply snap off the end of the spears.
In a large dish, season the asparagus with the olive oil, vinegar, garlic, salt, and black pepper. Toss with your hands so the spears are well-coated.
Let them marinate at least an hour if you have the time, or longer. If not, you can cook right away.
When ready to cook, preheat your grill to medium-high heat.
Arrange the asparagus spears on the grill in a manner that they won't fall through the grates. You can also use a grill basket if you have one.
Grill the asparagus for 3-8 minutes (depending on the thickness of your asparagus and the heat of your grill), turning occasionally, until they are tender and lightly charred.
Toss it back into the dish with the vinegar getting all the flavor over it, then transfer it to a platter.