In a small saucepan bring the vinegar to a simmer over medium heat.
Reduce the heat until just a few bubbles break through the surface.
Add the smashed garlic.
Cook at a slow simmer until about 1/4 cup of vinegar remains (about 20 minutes).
If you cook too quickly or it reduces too much, it will turn bitter rather than sweet.
Remove the sauce pan from the heat and let cool to room temperature (The syrup will continue to thicken as it cools).
Heat grill to medium heat.
Remove and discard all tough, woody ends from the asparagus spears.
Wash and pat dry.
Lightly coat the asparagus with the Hot Pepper Oil.
Season evenly with the salt and pepper.
Brush the cooking grate clean.
Lay the asparagus perpendicular to the bars on the grate.
Grill over direct medium heat with the lid closed as much as possible, until lightly charred and crisp-tender, 4-6 minutes, rolling the spears a couple of times and swapping their positions as needed for even cooking.
Arrange the asparagus on a platter or individual plates.
Remove the garlic from the syrup.
If the syrup is stiff, warm it briefly over medium heat.
Drizzle some of the syrup over the spears (you may not need all of it.).