Edited by VermontGal, Sondra C, Teresa, Kch674 and 9 others
An ancient tool, the mortar and pestle are still very useful around the modern house for crushing items to a fine paste or powder.
Pick the right mortar and pestle. Mortar and pestles are usually made in a matching set. Common materials are wood, stone, or sometimes hard clay. Although usually any will do, you will want to consider if you want your tools dishwasher-safe, if it will be easy to clean, the weight, and if breakage may be a problem, such as if dropped.
Use for its intended purpose. If you need something ground into a paste or powder, this is a great tool. If you need something chopped, pureed, or blended, you may be better off with another tool.
Get into the grind. Put your item to be ground into the bowl-like mortar. Take the pestle by the handle, and use a firm pressure while making a stirring-like motion in order to ground your material. If the item resists, you can try some firm but gentle pounding to start initial cracks (this happens often with peppercorns). Grind into your preferred consistency.
Clean your mortar and pestle after use. Cleaning depends a bit on the material of the mortar and pestle. If it is not dishwasher-safe (such as a wooden set), clean with warm water and dish soap. If your mortar is being used for only one, non-food-related purpose (such as grinding fish food) you might be able to skip this step.