Microwave the frozen udon noodles in the bag for 3.5 minutes at 600 W.
Cut the pork into bite-size pieces, thinly slice the Japanese leek diagonally, and thinly slice the shiitake mushroom. Coat in the yakiniku sauce. Cover with plastic wrap, and microwave for 1.5 minutes at 600 W.
Add the udon noodles into Step 2, and mix.
Remove the wrap, and microwave again for another 1.5 minutes at 600 W. Briefly stir, transfer to a bowl, then it's done.