Focus on Arts and Ecology

In the months leading up to winter in Hanoi, when the temperature starts to drop and a chilly breeze blows through the city, anticipation grows for a rare, unique delicacy – the palolo worm omelet, or chả rươi in Vietnamese.

The dish is made from the palolo worm (rươi) – an unsightly, two-inch-long sea creature. It’s mixed together with tangerine peel, herbs, minced pork and beaten egg before being fried over low heat. What results is an omelet that’s infused with a fruity zest and the rich, caviar-like flavor of rươi, yet avoids any resemblance to its most famous, unpalatable ingredient.

The mystery of the palolo worm

The palolo worm has a mysterious habit of “rising” and appearing in slithering masses on the ocean’s surface, but only on specific days related to the cycle of the moon. In Vietnam, this usually occurs in October and November. Their appearance corresponds with the ninth and tenth months of the lunar calendar. An old Vietnamese saying, “Tháng chín đôi mươi, tháng mười mùng năm,” translates as “the 20th day of the ninth month, the fifth day of the tenth month,” and refers to the times of year when a palolo rising can be anticipated, and the worms can be harvested directly from the waves that carry them.

The palolo worm is not unique to Vietnam. It also appears in many countries around the Pacific Ocean, including Japan, China and Indonesia, as well as the South Pacific islands. In fact, the name palolo originates from the Samoan language. In Samoa, the palolo worm is traditionally fried and served with toast, baked into a loaf, or even eaten alive.

In Vietnam, many farmers who had been harvesting rươi for centuries didn’t even know where they came from or why they appeared so suddenly. In reality, the worm is a bottom dweller and, when the time comes for reproduction, as determined by lunar cycles, it grows a detachable reproductive part at its rear, called the epitoke. This is a sac filled with either its sperm, which is brown-grey in color, or its eggs, which are blue-green. The sac then breaks off from the worm and, using its tiny, hair-like tentacles, swims to the surface and gathers with others to reproduce.

Meanwhile, the rest of the worm continues to enjoy an unbothered life on the seabed. It can even grow a new rear part to be released a second time, which is why the “palolo rising” can happen more than once a year. More importantly, this means the harvesting process is sustainable – as humans only catch a number of the adrift sacs, the worms can be consumed without greatly decreasing their population.

Catching and preparing rươi

Without exact knowledge of the days in which the worms would appear, catching rươi used to be a game of hide-and-seek. When they did, those living near the sea would bring their nets, leap into the swarms, and catch them by hand. The worms then became a vital and cherished source of food for the next few days, until they eventually rose again.

More recently, farmers in the northern coastal province of Hai Duong have started populating their lakes and paddy fields with the worms. They can live in the mud, and when they rise each year, the farmers empty the water from the lakes, making them easy to collect. Rươi are rarely eaten by the farmers now, though. Due to their financial value, they are all packed into ice boxes and sold to traders from Hanoi and China.

Before cooking, rươi needs to be boiled to remove their tentacles and fishy smell. The added fragrance from herbs and tangerine helps, too. Traditionally, the peel is dried before use, but it can be added fresh in thin slices. The dried variety, called trần bì, is also a traditional ingredient in Chinese medicine and cuisine, and its use is thought to balance the food and aid digestion.

Chả rươi as street food

At home, chả rươi is usually served with rice. When found in street food stalls around Hanoi, however, it is served, much like bún chả, with bundles of rice vermicelli and a bowl of sweet and sour fish sauce. These extras complement and counterpart the fatty taste of the omelet.

One of the most popular and long-running stalls selling this dish is Cha Ruoi Hung Thinh at 1 Hang Chieu Street. You can eat at tables within O Quan Chuong, an ancient gate to the city. They serve two different types of chả rươi, one with a larger proportion of worms, priced at VND30,000, and the other, with fewer worms than pork, at half the price. Those who come purely for the exotic taste of the worm apparently opt for the “more” option, while those who find the idea a bit grim choose the latter. Either way, it’s the season for it right now, so an ideal time to try and worm your way into one of the crowded chả rươi stalls.