Place udon noodles in a large heatproof bowl and cover with 4 quarts of boiling water. Let stand for 2 minutes or until noodles are pliable. Gently separate the noodles and drain in a colander. Transfer noodles to a large heatproof bowl, toss with the sesame oil and set aside.

In a large wok or saute pan over medium-high heat add 1 tablespoon vegetable oil and when hot add the cabbage and cook, tossing often, until it has wilted, about 5 minutes. Transfer the cabbage to the bowl with the noodles and set aside.

Heat 1 tablespoon of vegetable oil in the wok over medium- high heat and add the pork, breaking up the pieces and spreading it out in a single layer in the pan. Cook, undisturbed, for 3 minutes or until the pork is golden brown. Toss the pork and continue to cook until it is brown on all sides and it is no longer pink, about 1 minute longer. Transfer the pork to the bowl with the cabbage and noodles, cover and keep warm.

Heat the remaining tablespoon of oil in the wok over high heat and add the mushrooms, cook, tossing occassionally until the mushrooms are brown, about 3 minutes. Add the green onions, ginger and garlic and cook for 1 minute longer. Add the noodles, cabbage and pork back to the pan along with the mirin and tamari and cook until the sauce slightly thickens and the noodles are heated through, about 2 minutes. Add the chili garlic sauce and stir to combine. 

Serve immediately.