Add 2 quarts of water and 1 tablespoon of kosher salt to a large pot. Bring to a boil over high heat. Add the noodles and cook according to package directions. Drain but save at least ¼ cup of the pasta cooking water. Set aside.
While the noodles cook, add the vegan oyster sauce, cane sugar, tamari, vinegar, and sesame oil to a small bowl. Stir well to combine.
Melt the vegan butter in a wok or skillet over medium-high heat. When the butter starts to sizzle, reduce the heat to medium and add the garlic and green onions, reserving half of the chopped green parts. Sauté until the garlic is fragrant and the green onions are tender, being careful not to burn the garlic.
Add the sauce mixture and ½ cup of the noodle water to the wok and stir well. Bring to a simmer over medium heat and cook for 3 minutes.
Remove the pan from the heat. Transfer the cooked noodles to the sauce and toss well to coat.
Top with the remaining chopped green onions and serve hot.
