Bring a large pot of water to a rolling boil and add a pinch of salt. Drop in the udon noodles and stir gently to prevent sticking.
Cook the noodles for about 8-10 minutes until they are just al dente, with a slight bounce when tested. The edges should appear glossy and firm.
Using a slotted spoon, transfer the cooked noodles into a bowl of ice water to quickly stop the cooking process and lock in their chewy texture. Gently shake off excess water and set aside.
Heat a wok or large skillet over medium-high heat. Add a teaspoon of toasted sesame oil and swirl to coat the pan.
Add the sliced mushrooms to the hot pan and sauté for about 3-4 minutes, until they release their juices and turn golden brown with a slight caramelized edge.
Stir in the minced garlic and grated ginger, cooking for about 30 seconds until fragrant. The kitchen should fill with a warm, spicy aroma.
Pour in the vegetable broth and soy sauce, bringing the mixture to a gentle simmer. Let it cook for 2 minutes to meld the flavors and slightly reduce the sauce.
Add the drained, cooled udon noodles to the skillet and toss quickly to coat them in the sauce. Cook for another 1-2 minutes until the noodles are heated through and glossy, maintaining their chewiness.
Remove from heat and stir in the chopped green onions for a fresh, crisp contrast. Let sit for a minute to allow flavors to settle.
Serve immediately, garnished with extra green onions or sesame seeds if desired. Enjoy the bright, chewy noodles coated in a savory, smoky sauce.
