Cook Udon according to package directions. Preheat a large skillet and saute the shitake mushrooms in the oil until tender. Add the garlic and saute for 1 minute more. Add the miso and water and bring to a gentle boil. Lower the heat to a simmer and add the kale. Toss the mixture until the kale wilts down. Stir in noodles. Serve in bowls and add soy sauce to taste.