This stir-fry pairs broccoli and onion (or bell pepper) with satisfyingly starchy noodles. To mimic the flavoring-building char of high-heat wok cooking, we sear the broccoli in a hot skillet before adding the sauce ingredients. With saltiness, sweetness and umami, either oyster sauce or hoisin offers big flavor and lots of complexity. We think both are handy, must-have ingredients to keep in the refrigerator. A couple tablespoons of rice vinegar and fresh ginger brighten up the flavors.