It is a rich source of food, thanks to alluvial sediment and zooplankton, the worms offer lots of nutrition and a greasy taste, which can be used to make several dishes and delicacies of the north, including stewed clam worms with star fruit.

Chef Dinh Van Luong from Song Ngu Restaurant in Nghe An province, said he fries onions and pork together with some chopped ginger, green pepper, peels of mandarin, sliced turnip and star fruit.

Then he adds salt, sugar, fish sauce and pepper before adding water. When the water is boiled, he puts the scalded worms in and stews them for about 10-20 minutes over a medium fire.

“The final dish should be dry with almost intact forms of worms,” he said. “The fatty worm tastes sweet when combined with sour star fruit and the fragrance of herbs, which is good in winter,” he said.

Northern people often add eggs at the end of the cooking process and stew them for up to three hours.

Locals in Hai Duong province stew the ingredients in a clay pot and add some more bamboo shoots. The dish should be served hot with boiled rice.