How to Make It
In a food processor or blender, combine the sugar, oil, ginger, shallots and chile-garlic sauce and process until a coarse puree forms.
Arrange the tuna steaks in a 13-by-9-inch glass baking dish. Pour the marinade over the steaks and turn to coat. Cover with plastic wrap and refrigerate for 2 hours, turning once.
Light a grill or preheat the broiler. Season the tuna steaks on both sides with salt and pepper. Grill the steaks, turning once, for about 4 minutes per side for medium rare. Slice the tuna steaks across the grain and serve warm, at room temperature or chilled.