Using a food processor, puree lime juice, 2 tbsp. canola oil, sesame oil, fish sauce, garlic, 1/4 cup cilantro, salt, cayenne and brown sugar until sauce is pale orange and garlic is pulverized. Set aside.
Remove loosest, toughest outer leaves from cabbage and cut cabbage into 8 evenly sized wedges. Do not remove the stalk or inner core. Lightly brush wedges with canola oil.
Place wedges on the grill and loosely cover with aluminum foil. Cook for 5 to 7 minutes or until the edges of each layer are blackened and cabbage is beginning to soften. Flip each wedge over, cover the grill and cook for an additional 5 to 7 minutes on the other side. Remove cabbage when it is beginning to wilt, but is still firm in the middle.
Remove cabbage to a plate, arranging wedges neatly. Pour dressing over the top and serve immediately, garnishing with wedges of lime and extra cilantro sprigs.
Serves 8