If you have a carton of eggs in the refrigerator, you can have a nutritious breakfast, lunch or dinner for pennies. Protein foods are the most expensive items on the food budget, and when you compare the cost per serving to other protein foods, the egg comes out a winner.

If a dozen large eggs cost $1.09, multiply the cost by 2/3 to compare the cost per pound to other protein foods, according to the University of Kentucky Cooperative Extension. That's 72 cents a pound.

Eggs are so basic, we sometimes forget all the great things they do. Eggs give structure to baked goods (cakes, muffins, pancakes) as well as savory foods like meatloaf. They work as a leavener, thickener and binder in sauces like hollandaise and mayonnaise, and they give smoothness to everything from custards to truffles. On top of all their undercover work, eggs are nutritious and delicious on their own, whether poached, fried, scrambled, or made into an omelet or frittata, according to Fine Cooking.

When hard-cooked, eggs make great egg salad or deviled eggs. But a common complaint from cooks is that green ring around the yolk, which is a sign of overcooking. Cooks who boil eggs often opt for electric egg cookers, which eliminate the need to watch the clock while boiling or poaching eggs.

Chef'sChoice has an egg cooker that allows users to cook eggs to various degrees of "done-ness" in the same batch. Eggs can be combined to cook some as soft, others medium or hard-boiled, which eliminates the worry about undercooked or overcooked eggs.

No matter how you cook the egg, it's best if it's fresh. At some farmer's markets, you can pick up local eggs. To check for a nearby farmer, go www.localharvest.org and enter your ZIP code.

According to Sustainable Table, local, organic free-range eggs are super-rich in vitamins and minerals. Some organic farmers are offering omega-3 eggs, which are laid by birds fed organic flaxseed.

___

EGG SIZES, EGG COLOR EGG CETERA

Here are some tips for making the most of a carton of eggs.

Kitchen math: Eggs are sold in standard sizes: medium, large, extra-large and jumbo. Most recipes call for large eggs; if a recipe doesn't specify, assume it means large.

1 large egg = 2 ounces = 3¼ tablespoons (1 tablespoon yolk; 2¼ tablespoons white)

1 extra-large egg = 4 tablespoons

1 medium egg = 3 tablespoons

5 whole large eggs = about 1 cup

Don't have it? In recipes that don't call for a lot of eggs, substituting one size for another is usually not a problem. However, as the number of eggs called for increases, the difference in amount will become more pronounced. When substituting a different-size egg, use the equivalents above to figure out the total volume you'd get from large eggs, then use however many eggs you need to reach that volume.

How to choose: The most common eggs used in cooking are unfertilized hen eggs. Eggs can be brown or white (or even shades of pale green and blue), which is determined by breed. Fresh eggs are your best bet for flavor, and farm-fresh are a great treat. At the supermarket, check the carton for a date. Though salmonella is rare in eggs, people at risk should not consume raw or undercooked eggs. Pasteurized eggs, available at many markets, are a good alternative in such cases.

How to prep: Many recipes call for room-temperature eggs. To warm cold eggs quickly, put them in a bowl of warm water.

How to store: Store eggs in the refrigerator in the carton in which they came. They'll keep for several weeks, though they're best used within one week.

EQUIPMENT

Eggs don't require any special equipment, but here are some things that will make preparation easier.

As a rule, when cooking on top of the range, cooking is more even in heavy-gauge pots and pans. Baking dishes and pans of the proper size are particularly important for items that rise, such as breads, cakes and souffles.

BEATERS

Cooks once had to rely on muscle power to whip eggs. They used an assortment of large and small, flat and balloon-shaped whisks, many of which are still available. A really determined home baker could whip up an angel food cake by separating the egg whites onto a large platter and beating them vigorously with a hickory rod.

In 1870, the rotary hand beater was invented. The rotary beater beat out all competition, along with mountains of meringue, and is still a handy and inexpensive tool.

Today, most cooks use an electric stand mixer or a portable electric mixer. Blenders and some food processors can whip up a whole egg, an egg yolk or a mixture but do not produce stiffly beaten egg whites.

BOWLS

There has long been a great controversy about the merits, if any, of using a copper bowl to produce volume in beaten egg whites. The copper in the bowl reacts with the conalbumin of egg ...