Countless recipes start out by sautéing a little diced onion, making this vegetable one of the most indispensable pantry staples. When a recipe simply calls for onions, choose yellow onions, the best all-purpose onions. Since they are inexpensive and readily available, they're used more than any other type. They have the strongest flavor of all the globe onions, so they're best when cooked and are the first choice for an aromatic base for stocks and broths. White onions can also stand in for yellow onions, and they are good slicers for burgers or sandwiches. Spanish onions are similar to yellow onions, but they're larger. Beyond these types, there are several specialty varieties, including red onions, cippolini, pearl onions, and super-sweet Vidalias.
1 medium-large = 8 oz. = about 1-1/2 cups chopped
If you're out of onions, shallots or leeks can substitute in a pinch.
Buy firm bulbs with no soft spots, bruises, or other signs of damage. The necks should be tightly closed. They should be heavy for their size, with dry, papery skins.
Peel before using. How you cut an onion has a dramatic effect on the final texture. If you want the onion to blend seamlessly into the dish, mince it. For a little more presence, dice it. If you want it to be unmistakable, slice it. Cutting the onion "with the grain," from root to blossom end, will give you slices that hold together during cooking and retain their shape well. Slicing "across the grain," which creates rings or half moons, release more moisture and lose their crispness faste and soften more quickly when cooked.
Keep in a cool, dry, well-ventilated spot.