Preparation Spread sesame seeds on large plate. Sprinkle beef with salt and pepper; coat with sesame seeds. Heat vegetable oil in heavy large skillet over high heat. Add onion; stir-fry 1 minute. Add asparagus; stir-fry until crisp-tender, about 2 minutes. Add beef; stir-fry until brown, about 2 minutes. Reduce heat to medium. Add 1/3 cup water and hoisin sauce. Cook until sauce is bubbling and coats beef and vegetables, stirring often, about 2 minutes. Stir in sesame oil. Season with salt and pepper.
Preparation Spread sesame seeds on large plate. Sprinkle beef with salt and pepper; coat with sesame seeds. Heat vegetable oil in heavy large skillet over high heat. Add onion; stir-fry 1 minute. Add asparagus; stir-fry until crisp-tender, about 2 minutes. Add beef; stir-fry until brown, about 2 minutes. Reduce heat to medium. Add 1/3 cup water and hoisin sauce. Cook until sauce is bubbling and coats beef and vegetables, stirring often, about 2 minutes. Stir in sesame oil. Season with salt and pepper.