How to know when olive oil is hot enough

The great dilemma. We think the oil has reached the right temperature and only realise it hasn’t when we’ve already added the ingredients. Or the room fills with smoke because we’ve left it to heat up too long. The trick is to bring your palm close to the oil (without touching it!) and check that the temperature is rising. Then use a wooden stick to see whether bubbles form around it when you put it into the oil. Alternatively you could use a piece of bread or some of the food you’re about to cook. The bubbles are key—they show the oil is hot enough.