¼ cup low-sodium tamari or soy sauce 2 tablespoons rice vinegar 2 tablespoons maple syrup 1 tablespoon toasted sesame oil 1 tablespoon gochujang or 1 teaspoon sriracha ½-pound-bunch oyster mushrooms or sliced shiitake mushrooms 4 to 5 ounces noodles 1 tablespoon sesame or neutral cooking oil 1 cup julienned or coarsely shredded carrots 6 green onions, cut into 1-inch pieces 4 baby bok choy, stems trimmed, outer leaves separated, and small inner leaves left attached 2 teaspoons toasted sesame seeds for garnish (optional