This is a very simple and quick meal- I served it with quick steamed broccoli.
Put a medium pot of water on to boil. Cook one bundle udon in the water until al dente and drain. Dress noodles with a few drops of sesame oil. Peel and dice an onion. Saute in 1 tbs. oil until translucent. Add ten sliced mushrooms (I used button, but -5 shiitake would be good. I think the original recipe was all about Crimini.) and fry until browned. Add the noodles, 1 tbs. soy sauce, and 1 tbs. mirin (or white wine). Fry for about a minute, until uniformly warm. Eat.
Make quick steamed vegetables by washing the vegetable, placing it in a microwave safe bowl, covering the top of the bowl with saran wrap, and microwaving it for three minutes. There.