A cooking leaf is a plant part used in the preparation of a dish or its method of cooking. One main example is the rosemary leaf that is used to season food as well as provide flavor to sauces. In general, leaves are often chewed before they are added to dishes or they can be steeped in liquids such as herbs and vinegar. The leaves may have been leftover from a previous dish and can easily be added to future meals along with other fresh ingredients. When cooking with herbs and leaves this is a very good way to use up your leftover herbs and leaves. Leafy greens such as spinach, lettuce, arugula, and dandelion are also used in many dishes, because they are low in calories the leaves can be simply added to the dish without detracting from its flavor. The flavor, however, can easily be changed by changing the type of leaf and cooking technique.