In an electric blender or food processor, purée garbanzo beans, red peppers, lemon juice, tahini, garlic, cumin, cayenne, and salt. Use long pulses to process until mixture is fairly smooth and slightly fluffy, scraping down the sides in between pulses. Transfer to a serving bowl and refrigerate for at least 1 hour or up to 3 days.
Return to room temperature and sprinkle with chopped parsley before serving.