In bowl of food processor, place canola oil, rice vinegar, sugar, salt, lemon grass, ginger and garlic cloves. Process until lemon grass is chopped fully, about 3 minutes. Transfer to glass bowl. Add chicken thighs to bowl. Cover and refrigerate at least two hours, or overnight, or up to 2 days.

Prepare charcoal or gas grill, or preheat oven broiler. Thread chicken pieces and scallions, alternating. Place on grill and cook, turning once, until chicken is firm and opaque, about 6 - 8 minutes per side. Plate on serving platter and sprinkle with sesame seeds.