Ingredients: For the Sauce: 2 tablespoons oyster sauce 1 tablespoon dark soy sauce 1 tablespoon mirin 1 tablespoon light brown sugar 1 teaspoon chili sauce (such as Sambal Oelek) For the Noodles: 16 ounces fresh udon noodles 2 tablespoons neutral oil 1/2 small onion, thinly slice…