Extra virgin olive oil

You can use it for roasting, sautéing and shallow-frying as well as dressings. For frying, heat it over a moderate flame and add the food once the oil is hot but not smoking; smoking means it is overheating.

Keep the bottle tightly closed in a cool, dark cupboard, away from the oven and direct sunlight. Use it within a few months of opening for the freshest flavour; a dark glass bottle helps protect it from light.

Fresh oil smells fruity, grassy or peppery. If it smells like stale nuts, wax or crayons, or tastes flat and greasy, it has probably become rancid and is best discarded.

Drizzle it over tomato salad, grilled vegetables, beans, soup or toast, or whisk it with vinegar and mustard for a dressing. It is also a finishing touch for dishes such as hummus and minestrone.

Extra virgin olive oil is extracted from olives without chemical refining and must meet quality standards for flavour and acidity. Ordinary olive oil is generally refined oil blended with some virgin oil, so its flavour is milder.

Often, yes: use about three-quarters as much oil as the butter called for, since butter contains water as well as fat. It works especially well in cakes and savoury bakes, though it will not give pastry the same firm, flaky texture.

Yes. A tablespoon of about 14 g provides 8.1 µg of vitamin K. It is also almost entirely fat, so even a small drizzle contributes 126 kcal.