Sake, a Japanese rice wine, is available wherever fine wines are sold. Mirin, a Japanese sweet rice wine used in cooking, is similar to sake but with a lower alcohol content and a higher sugar content. It may be found in the Asian aisle of some supermarkets or in Asian grocery stores. If using wooden skewers, soak thoroughly in water for at least 30 minutes before threading with beef. This prevents them from burning when on the grill. To toast sesame seeds, heat small fry pan on medium heat. Add sesame seeds; cook and stir 2 minutes or until golden brown and fragrant. Immediately pour out of hot pan to avoid over-toasting.