Tastes like caviar: worm omelette, a seasonal Vietnamese delicacy, draws diners from miles around

• Ragworms appear on the sea’s surface on certain days of the lunar cycle in autumn. In Hanoi, Vietnam, they are harvested to make a delicacy called cha ruoi
• The worms are boiled, then mixed with minced pork, tangerine peel, herbs and eggs and fried. ‘Delicious and unique,’ says a diner who travelled 10km to try one