In a shallow pan, soak skewers in cold water for 1 hour, then drain and set aside.
Preheat grill to high. Snap off the woody bases of the asparagus and discard. Skewer 4 or 5 asparagus spears together, using the toothpicks or 2 bamboo skewers, forming a raft shape.
In a small bowl, combine the sesame oil, soy sauce, and garlic and stir with a fork to mix. Brush this mixture on the asparagus rafts on both sides. Season the asparagus with a little salt and lots of pepper.
When ready to cook, place the asparagus rafts on the hot grate and grill until nicely browned on both sides, 2 to 4 minutes. Sprinkle with the sesame seeds as they grill. You can serve the asparagus as rafts or unskewered.