USCIS - "If you are a worker with exceptional ability in the sciences, arts, or business, you may apply to waive the requirement that you have a job offer if such a waiver would be in the national interest. To apply for a national interest waiver, you must submit Department of Labor Form ETA-750B. Please see the Department of Labor's Employment and Training Administration for more information."
見 Application Procedures 之第三段
Or google "NIW ETA-750B"