Eggs provide nearly all the nutrients, proteins, fats, vitamins and minerals essential for life. One ingredient that may seem less essential, but is vital to the cooking of an egg, is air. It?s that tiny pocket of air that is directly related to the age and quality of an egg.

The air pocket in an egg lets the developing chick breathe. But eggs meant for consumption are cooled and stored and their water content starts to evaporate making the air pocket bigger. Thus the larger the air pocket, the staler the egg. Stale eggs, with their flat yolks and watery whites, spread to all corners of the frying pan.

To deduce how fresh an egg is try this simple test: place the egg in a tumbler of cold water. If it sinks to a completely horizontal position, it is fresh; if it tilts up slightly or to a semi-horizontal position, it could be up to a week old; if it floats into a vertical position, then it is stale. In my opinion, three weeks is the maximum time to keep eggs.

Eggs should be stored in the refrigerator but should always be removed from it a good half hour before cooking. The reason: eggs are better used at room temperature.

Today, eggs are out of the firing line on the cholesterol front, being low in saturated and hydrogenated fat. However, eggs can harbour a bacterium called salmonella. Cases of food poisoning, or even death, from eating eggs are isolated but do occur. Therefore, the only way we can be absolutely certain of not being affected is by only eating eggs that are well cooked, with hard yolks and no trace of softness at all.

There is no difference between a brown and a white egg. The colour of the shell is determined by the breed of hen that lays it. When baking, the best way to measure is by comparing the eggs you are using, weight for weight.

When it comes to whisking egg whites, ensure that there?s not even the slightest trace of egg yolk and that the bowl is grease-free (run a slice of lemon round the whisk and the bowl).

Ingredients: 4 10-inch flour tortillas; 2 medium ripe avocados, peeled, seeded, and mashed, to fill about 1 cup; 11/3 cup fresh spinach, sliced; 4 hard-cooked eggs, quartered; 1 cup thinly-sliced mushrooms; 1/2 cup low-fat yoghurt; 1/4 to 1/2 cup tomato salsa; green onions, sliced; tomatoes, coriander, chopped

Method: Lay tortillas on chopping board. Spread each with 1/4 cup avocado. Top each with 1/3 cup spinach, 1 egg, and 1/4 cup mushrooms. Dollop with 2 tablespoons yoghurt and salsa to taste. Roll each burrito style. Cut burrito in half and tie each half with green onion strips, if desired. Garnish with chopped fresh tomatoes and cilantro, if desired.

To hard cook eggs, place them in a single layer in saucepan with enough tap water to cover at least 1 inch above them. Cover pan and quickly bring to a boil. Turn off heat and remove pan from burner to prevent further boiling. Let eggs stand in water with cover on for about 15 mins. Run cold water over eggs until completely cooled. Refrigerate in their cartons.