Loomi is an Middle Eastern spice. To make loomi ripe limes are boiled in salt water then sun-dried until the flesh turns dark in color. The resulting spice, called loomi, is often used to impart a distinctive citrus aroma and a sour tang to and meat and legume dishes. In Iran powdered loomi is also used to flavor basmati rice. Dried limes are available in whole, crushed or powdered form.
You can purchase ground lime (loomi) or ground lemon (lemon omani) at Middle Eastern grocery stores or you can purchase it online at Amazon.com: Ground Limu Omani