A very thin, white noodle similar to udon but cut very thin. Eat hiyamugi cold with a dipping sauce. Hiyamugi take about 5 minutes to cook. After cooking rinse in cold water and ice to chill and stop the cooking process.
Find this noodle in Asian grocery stores dried in small bundles. Sometimes you can find them at Whole Foods Markets. Or, buy online at Amazon.com.