Preparation

• Heat 3 Tbs. of the grapeseed oil in a wok or a large, deep skillet over medium heat, and swirl to coat the pan. When the oil shimmers, add the mushrooms in batches, and sear, turning occasionally, until golden brown in places, 3 to 4 minutes per batch. Transfer to a plate lined with paper towels, and salt generously. Add the remaining 2 Tbs. grapeseed oil to the pan. Add the 1 cup scallions, garlic, and ginger. Cook, stirring constantly, until just fragrant, about 30 seconds. Add the carrot, zucchini, and bell pepper. Cook, stirring frequently, until the vegetables begin to soften, about 2 minutes. Add the watercress, and cook until it just starts to wilt, tossing frequently, about 1 minute. Lower the heat to a simmer, add the mushrooms, noodles, oyster sauce, and stock. Cook, tossing frequently, until the mushrooms and noodles are just heated through, about 3 minutes.
• Add the lemon juice, and season to taste with salt and pepper. Transfer to a large platter, drizzle with the sesame oil, garnish with the reserved scallion greens, and serve.