In a medium microwave-safe bowl, cover the chiles with water and microwave at high power until softened, 5 minutes. Let cool slightly. Transfer the chiles and 1/2 cup of the soaking liquid to a blender. Add the garlic, oregano and 4 tablespoons of the canola oil; puree until very smooth. Strain the puree and season with salt and pepper.
Season the steaks with salt and pepper and rub with half of the chile puree. Transfer the steaks to a resealable plastic bag and refrigerate overnight.
In a medium saucepan, heat the remaining 2 tablespoons of oil. Add the onion and cook over moderate heat until softened, about 7 minutes. Add the remaining chile puree and cook, stirring, for 2 minutes. Add the brown sugar and vinegar and simmer for 3 minutes. Season the glaze with salt and pepper.
Light a grill or preheat a grill pan. Brush the steaks with oil and grill over moderate heat until medium-rare, 12 minutes; brush with 3 tablespoons of the glaze in the last 2 minutes. Let the steaks rest for 5 minutes before slicing 1/2 inch thick. Serve the steaks with the remaining chile glaze.