In a small bowl, whisk together the water, soy sauce, vegetarian mushroom sauce, sugar, cornstarch, and sesame oil until the cornstarch is completely dissolved.

In another small bowl, stir together one tablespoon of the vegetable oil with the ginger and garlic. Heat another tablespoon of oil in a 12-inch nonstick skillet over high heat until it just begins to smoke. Add the mushrooms and cook, stirring occasionally, until they are lightly browned and tender, 6 to 8 minutes. Add the scallions and cook until they have wilted, about 2 minutes, then transfer the entire mixture to a large bowl.

Heat the remaining tablespoon of oil in the empty skillet and add the bell peppers and cabbage. Cook until the vegetables are tender-crisp and show spotty brown charred marks, about 8 minutes. Clear a space in the center of the skillet, add the ginger-garlic mixture, and cook, mashing the paste into the pan until fragrant, about 30 seconds, before stirring it into the rest of the vegetables.

Pour the sherry into the skillet and cook until the liquid has nearly evaporated, 30 to 60 seconds. Stir in the reserved mushroom mixture and the sauce and simmer until the liquid has thickened and coats the vegetables, 1 to 2 minutes; cover and set the skillet aside while you finish the noodles.

Bring 4 quarts of water to a boil in a large pot. Add the noodles and cook, stirring often to prevent sticking, until they are tender. Drain the noodles thoroughly and return them to the pot. Add the cabbage and mushroom mixture along with the chili-garlic sauce and toss to combine. Serve hot.