"The Qing Lu Lu" records: "The onion harmonizes the flavors of many ingredients, just as licorice root is essential in medicine." This comparison of the onion's role in cooking to licorice root in medicine is truly apt. But how should one use onions in cooking?
In cooking, onions can be used as both an auxiliary ingredient and a seasoning. For ingredients with strong fishy or gamey flavors, such as the offal and eggs of aquatic animals, poultry, and livestock, adding scallions during cooking not only helps to mitigate the cold nature of shellfish but also has anti-allergic effects.
First, the shape of the processed onion should be consistent with the main ingredient. Generally, the onion pieces should be slightly smaller than the main ingredient, but this can be flexible depending on the cooking method. For example, "Braised Fish" requires the onion to be cut into sections and cooked with the fish. "Dry-Braised Fish" calls for minced onions to match the other ingredients. For "Steamed Fish," a whole scallion is placed on top of the fish and removed after it's cooked, leaving only the scallion's aroma. For "Fish Ball Soup," the scallion is soaked in water, and only the scallion juice is used to avoid affecting the color of the fish balls. For "Fish Soup," the scallion is typically cut into sections, fried, and then simmered with the fish, as the fried scallion has a strong aroma that removes the fishy smell. After the soup is cooked, the scallion sections are removed, leaving the soup clear and not cloudy. Minced scallion or scallion juice is mainly used for dressings in cold dishes to obtain a light, fragrant scallion oil flavor.
Braised Tofu with Scallions
Second, the cooking method directly affects how the onion is handled in the dish. For example, in cooking methods that are completed quickly over high heat and often involve direct thickening in the wok, the onion used is generally cut into one-inch sections, such as in "Scallion and Egg Stir-fry" or "Braised Sea Cucumber with Scallions." Additionally, when making grilled fish, it is best to use whole scallions to line the bottom of the pan, not smaller sections or minced scallions. This prevents the scallion aroma from dissipating too early and also prevents the "sticking to the bottom of the pan" problem.
Finally, it should be noted that it is best not to add scallions when making soups, lest their strong flavor overpowers the natural umami of the soup.