Marinate the beef: Cut the flank steak across the grain into slices 1/4 inch thick. In a shallow dish large enough to hold the meat, stir together the sake, soy sauce, vinegar, honey, sesame oil, ginger, garlic, red pepper flakes and coriander. Add the flank steak and stir to coat thoroughly. Cover and let stand for at least 30 minutes to 2 hrs.

Meanwhile, soak 12 bamboo Skewers in cold water for at least 30 minutes. Prepare a gas or charcoal grill for direct heat grilling over high heat and oil the grill rack. Or, preheat a broiler.

Drain the skewers. Remove the meat from the marinade then thread meat onto the skewers, dividing the meat evenly. Place the skewers on the grill rack, or put on a rimmed baking sheet and place under the broiler. Cook, turning once or twice, until seared, 3 to 4 minutes total for medium-rare.