Teriyaki Beef

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Ingredients

1. 2/3 cup soy sauce
2. 1/2 cup mirin
3. 1/2 cup sake
4. 1/3 cup sugar
5. 4 scallions, minced
6. Four 1/4-inch-thick slices of fresh ginger, smashed
7. 4 garlic cloves, smashed
8. 1 tablespoon plus 2 teaspoons Asian sesame oil
9. 1 1/2 pounds sirloin steak in 1 piece, cut about 1 inch thick
10. Salt and freshly ground pepper
11. Sweet Potato Packets

1. In a saucepan, combine the soy sauce, mirin, sake, sugar, scallions, ginger, garlic and 2 teaspoons of the sesame oil. Bring to a boil over moderate heat and cook until reduced to 1 1/4 cups, 8 to 10 minutes. Strain the sauce into a small bowl.
2. Light a grill or preheat the broiler. Brush the steak with the remaining 1 tablespoon of sesame oil and season generously with salt and pepper. Grill or broil the steak, basting with some of the sauce, for 4 to 5 minutes per side for medium rare. Let rest for 5 minutes, then thinly slice the steak on the diagonal and serve with the Sweet Potato Packets. Pass the remaining sauce separately.