Chefs often add chopped green onions, also known as scallions or spring onions, at the end of a meal or during the final stages of cooking for a few reasons:
Freshness and color: Green onions have a mild and delicate flavor that can easily get lost if cooked for too long. By adding them towards the end, their fresh and vibrant green color is preserved, making the dish visually appealing. The bright green hue also adds a pop of color, enhancing the overall presentation of the meal.
Texture: Green onions have a crunchy texture, especially the green parts. Cooking them for an extended period can soften them, and they might lose their characteristic crunch. Adding them at the end ensures that they retain their pleasant texture and add a desirable contrast to the dish.
Flavor balance: Green onions have a mild onion flavor that can become overpowering when cooked for a long time. By adding them towards the end, the onion flavor remains more distinct and fresh, contributing to the overall flavor balance of the dish.
Aroma: Freshly chopped green onions have a lovely, aromatic quality that can elevate the aroma of the dish when added as a garnish. It provides a burst of freshness that might be lost if cooked with the rest of the ingredients.
Nutritional benefits: Green onions contain essential vitamins and minerals. Adding them as a garnish ensures that their nutritional value is retained, as prolonged cooking can lead to nutrient loss.
While adding green onions at the end is a common practice, there are some dishes and cuisines where they are cooked as part of the main ingredients. It ultimately depends on the specific recipe and the desired outcome of the dish. In some cases, green onions may be used both as a cooking ingredient and as a garnish to create different layers of flavor and visual appeal.