Technically a legume, and not a tree nut, peanuts are grown in the southern United States. Delicious roasted and eaten out of hand, their strong flavor stands up well to hot chiles in Thai and Chinese cooking. On the sweet side, their often added to peanut-butter cookies.
5 to 5-1/2 oz.(whole shelled) = 1 cup coarsely chopped = 1 cup plus 2 Tbs. finely chopped = 1-1/4 cups ground
Nuts in the shell are usually the very freshest and best-tasting. If buying peanuts in the shell, look for whole, clean shells with no blemishes, holes, or cracks. When choosing nuts out of the shell, look for plump, unbroken nutmeats. Avoid those that are discolored or shriveled. These are the peanuts you want if a recipe calls for raw peanuts. If a recipe calls for salted peanuts, look to the ingredient list on the package—if it reads peanuts, oil, and salt, it's the right nut. These peanuts go by a number of names, including roasted, cocktail, and Virginia peanuts. (None of these peanuts are really roasted; they're fried, usually in peanut oil, and their flavor is rich and purely peanut.) Unless a recipe specifically calls for them, avoid "dry-roasted" peanuts for cooking and baking—they tend to be seasoned with spices and flavorings that don't always go with the other flavors in a recipe. Dry-roasted peanuts, as the name implies, are cooked in an oven by forced hot air, and oil is not in the ingredient list.
Remove nuts from shells if necessary and peel away their skin before using.
Vaccuum-packed jars of shelled peanuts will last for a year unopened. Once opened, shelled peanuts should be refrigerated. Unshelled peanuts will last for weeks stored wrapped in a cool dry place and for months if refirigerated.