Sesame is a fascinating flavouring because it has so many different guises. The seeds can be roasted and sprinkled on food for a nutty crunch, ground into thick pastes and sweets, or pressed to extract the rich oil. The leaves are popular in Korean cuisine for their herb, slightly bitter taste. Raw sesame seeds have a mild fragrance and taste that is enhanced when they are roasted. You can do this in a dry (not oiled) pan or in the oven, but they must be mixed constantly because they burn easily. If you travel to Japan, look in kitchen-gadget shops for a special sesame-seed cooker - a small, flat pan with a fine-mesh latched screen that allows you to roast the seeds over a flame without scattering them. Sesame oil is wonderfully fragrant and pervasive; a little goes a long way. Chinese sesame oil is made by first roasting the seeds to bring out the flavour. The thick oil is dark and distinctively nutty smelling, but because it is expensive some manufacturers mix sesame oil with cheaper vegetable oils. Check that the label on the bottle says it is 'pure sesame oil'. Chinese sesame oil has a low smoke point so it can't be used for frying. Drizzle it on dishes at the last minute - it's good in soups, meat and vegetable dishes. Lighter-coloured sesame oils are made from unroasted seeds and have a milder flavour. Sesame pastes are often used in Middle Eastern cooking. Tahini is made from roasted or unroasted seeds ground into the thick paste. It is used to give a certain depth of flavour to dishes such as babaganoush (made with roasted eggplant, garlic, olive oil and lemon juice) or hummus (made with chickpeas), and is sometimes thinned with water and lemon juice and served with vegetables. Most Middle Eastern recipes call for the light (unroasted) sesame paste because its milder flavour doesn't overwhelm the balance of the dishes. Chinese cuisine, however, always calls for roasted sesame seed paste because it has a deeper flavour. It is used in marinades and cold dishes such as gai see fun pei (mung bean sheets with cucumber and shredded chicken), for which the paste is mixed with soya sauce, sugar and garlic. The only time I have seen sesame leaves being used is in Korean cuisine. The large leaves look similar to the ragged-edged shiso leaf but the flavour is much milder and less distinctive. They are used as wraps for barbecued meats, and are marinated with chilli paste and garlic and served as a fresh-vegetable side dish.