Chop mushrooms or chilies in a food processor until fine.Place in a pot with the oil and heat until mixture begins to bubble. Let cook 10-15 seconds and remove from heat. Swirl until just warm. Strain into a bowl through 4 layers of cheesecloth. Squeeze well to extract as much oil as possible. Pour into a sterilized jar or bottle, seal tightly, refrigerate and use within one week for best flavor.
Experiment with combinations of dried, fresh and smoked chilies to add different flavor dimensions to your oil, not just heat. Try fresh poblanos, jalapenos and serranos or dried anchos and pasillas. Roast one of the fresh or dried chilies to add flavor. Add black pepper to the mix. It makes a truly amazing oil. Mushroom oil can be made from packaged, dried mushrooms such as porcini and shiitake. Mushroom hunters can dry their less than perfect specimens and use them for oil. If you filter through coffee filters, rinse them and squeeze dry before use. You will need some patience and probably several filters. Pour the oil little by little and stir occasionally. You will recover almost all the oil if you use dried chilies, however, the more fresh chilies, the les chili oil since the oil will bind and be hard to separate after being infused.