Place a slice of sukiyaki-cut beef flat on your work surface. Place three pieces of baby asparagus on the edge near you. Roll the beef carefully (don't tear them with heavy hands!) to seal the asparagus. Repeat until all the asparagus have been wrapped or until there are no beef slices left to wrap them with.
Arrange the beef-wrapped asparagus side by side in a single layer.
Place one tablespoon of rice flour in a strainer. Hold the strainer above the leftmost wrapped asparagus and, while moving the strainer slowly towards the right, tap gently.
Turn the beef-wrapped asparagus over. Repeat the flouring procedure with the remaining rice flour.
Make the teriyaki sauce. Mix together the sake, mirin, soy sauce, and the optional ginger, if using.
Heat enough cooking oil in a pan to reach a depth of one-fourth inch.
Fry the beef-wrapped asparagus in batches of four or five. DO NOT overcook them. Just brown and sear then scoop out and move to a plate.
When all the wrapped asparagus have been browned and seared, pour the teriyaki sauce in the pan. Boil gently for a minute.
Arrange the fried beef-wrapped asparagus in the pan in a single layer. Cook over high heat, rolling them in the sauce, until the meat has soaked up all the sauce.
Transfer the beef-wrapped asparagus to a plate. Sprinkle with toasted sesame seeds and serve at once.