Onions are versatile ingredient that vary in flavor, texture, and chemical composition. Many peoples select onions without considering the specific variety, but the specific variety of onion you select will change a flavor of a dish. An onion can provide a sharp and pungently flavor, or an onion can provide a sweet and subtle flavor.
The difference in onion flavor exist because different onion contain different levels of sugars and different levels of sulfur compound. Yellow onions contain high level of sulfur compounds, and yellow onions also provide a savory foundation when you cook yellow onions for long period of time. Because yellow onions have a pungent flavor when raw, you should use yellow onions for application that involve long heat applications, such as soups or roasts.
How to Choose, Store, and Cut Onions
When you apply heat to yellow onions, the sharp edge of the yellow onions dissolve, and the yellow onions become a savory base for protein. Additionally, sweet onions like Vidalia or Walla Walla onions contain high levels of sugar and low level of sulfur compounds. Because sweet onions have high sugar content, sweet onions are best used when you want a sweet flavor, and often people slice sweet onions thinly for burgers or grilled to allow the sugars in the sweet onions to caramelize.
Red onions and white onions provides different culinary function based off their color and flavor profiles. Red onions has a mild sweetness, and red onions are often used in raw applications like salads or taco because red onions provide a visual color. Red onions are also used for pickling because the pigment in red onions remain stable in brine.
White onions provide a sharp and clean crunch, and white onions are often used in Mexican cuisine because the acidity of white onion cuts through fatty meat. However, white onions dont have the same long-term storage capability that yellow onions have, so white onions must be used more frequently. Other type of onions, such as shallots, leeks, and scallion, serve specific purpose in cooking.
Shallots provide a garlic like flavor that is more delicate then the flavor of a standard onion bulb. You can use shallots in vinaigrettes and fine sauce because shallots are less heavy than standard onion. Leeks provide a mellow and buttery richness to stocks, while scallions provide a fresh and brightly flavor to a dish.
You must store onion correctly to prevent onions from spoiling or sprouting in your pantry. Yellow onions are hardy and can last for month if you keep yellow onions in a cool and dark place. However, sweet onions loses moisture quickly, and green onions requires hydration to remain crisp.
You should never store onions next than potatoes because potatoes release moisture and gases. These gases and this moisture cause onions to rot or cause onions to sprout sooner than is ideal. Therefore, you should keep onions and potatoes in separate and breathable container to reduce food waste.
You can also manage the physical process of slicing onions to reduce the irritation cause by onion gases. When you slice an onion, the cell of the onion break and release gases, and these gases cause your eyes to tear. You can mitigate this reaction by chilling the onion before you slice the onion.
Additionally, you should use a very sharp knife when you slice an onion. A dull knife mash the cells of the onion, and a dull knife cause the onion cells to spray irritating compound into the air. If you use a sharp knife, the knife will slice through the cells without mashing them, and a sharp knife will reduce the amount of gas released into the air.