Cut or tear 1 pound wild mushrooms into bite sized (1”-2”) pieces.
Cut 5 scallions crosswise into 5” pieces.
Position a rack as close to the broiler element as possible and preheat the broiler.
Bring a large pot of water to a boil.
Arrange the mushrooms and scallions on a large rimmed baking sheet and drizzle generously with olive oil.
Place under the broiler and roast until deeply caramelized and crispy, about 5 minutes, shaking the pan halfway through.
Remove from the oven and season with salt and pepper.
In a small bowl, whisk together 2 tablespoons plus 1 teaspoon soy sauce, 1 tablespoon toasted sesame oil, 1 tablespoon dark brown sugar, 1 tablespoon maple syrup, and 1 finely grated large clove of garlic.
Cook the dangmyeon noodles according to package instructions.
When the noodles are done cooking, drain them and add them directly to the sheet pan with the roasted mushrooms.
Pour the dressing over the noodles and toss everything together with tongs.
Transfer the japchae to a large platter and sprinkle with sesame seeds.
