mirin • sake • soy sauce • dashi • sugar • sirloin beef, sliced into 1/4- to 1/8th-inch strips • firm tofu, cut into 1-inch cubes • mushrooms, sliced (shiitake, portabello, button, enoki or a variety) • yellow onion, sliced into thin rings • scallions, cut into 2 inch pieces • small head bok choy or napa cabbage, leaves cut into 1- to 2-inch segments • short grain rice •