If using dried udon noodles, prepare according to directions on package (see notes).
Heat the canola oil (2 tablespoons) in a large deep skillet or wok over medium heat. Add the light green and white parts of the green onions (making sure to reserve about 1/2 cup of the darkest green parts) and the minced garlic (2 cloves). Sauté for about 2 minutes, until onions are softened and garlic is toasted and fragrant.
Add the sliced shiitake mushrooms (8 oz.) to the skillet and sauté until browned and softened, stirring occasionally (about 5 minutes).
While the mushrooms are cooking, make the sauce. In a small bowl or glass measuring cup, mix the soy sauce (1/4 cup), fresh ginger (1 tablespoon), sesame oil (2 teaspoons), rice vinegar (1 tablespoon), chili garlic sauce (2 teaspoons), honey (1 tablespoon) and water (1/3 cup).
Add the sauce and the prepared noodles to the skillet. Stir together. If things are sticking to the bottom, add 1/4 cup of water and use a wooden spoon to scrape anything from the bottom of the skillet.
Add the dark green onion slices (1/2 cup) as well as the basil/cilantro leaves (1/4 cup) if using. Stir together and serve.
Notes
Frozen Udon Noodles can be found at Asian markets or some other grocery stores and come already cooked - they just need to be defrosted. Dried may be more common in your store - these can be prepared by boiling or microwaving depending on type (follow the directions on the package). Refrigerated may also used right away (though I've heard frozen have the best texture). If using dried, use 8 oz. (16 oz. dried is different than 16 oz. fresh).
Make it gluten-free by using gluten-free Udon noodles or another GF noodle, and by using GF soy sauce or a suitable alternative.
Make it vegan by swapping out the honey for brown sugar or another vegan sweetener.
Add protein like tofu, chicken, beef, or shrimp for an extra hearty boost.