In a large bowl, combine 1/2 cup teriyaki sauce, 2 tablespoons cornstarch, 1 teaspoon crushed red pepper, and 1/2 teaspoon ground ginger. We add 2 pounds thinly sliced flank steak, and toss it to coat completely. Then, in a large skillet or wok, over high heat, in 1 tablespoon vegetable oil, we cook the steak mixture for about 5 to 7 minutes, stirring constantly, until the steak is cooked through. Then place it on a serving platter, and for garnish and crunch, top it off with some salted peanuts and thinly sliced scallions.