Despite its peculiar appearance, a sea creature with sprawling tentacles found in the central coastal provinces of Vietnam is gaining popularity as a local delicacy, especially when simmered with banana stem.

rum biển bếp bên sườn đồi.gif
Though technically a type of sea cucumber, rum bien has a tubular, slippery body with an earthy gray tone. Photo: Bep Ben Suon Doi

Known as rum bien, this marine mollusk is native to the coastal strip (locally called bai ngang) in provinces like Thanh Hoa, Nghe An, and Ha Tinh. Also referred to as sea cucumber or bong thua in local dialects, this variant differs significantly from those in northern provinces like Hai Phong and Quang Ninh. It is larger in size and has a distinct appearance.

Rum bien burrows deeply into sandy seabeds, with its body expanding in the middle and narrowing toward both ends. Its mouth is shaped like a funnel, surrounded by multiple tentacles resembling whiskers that help it scavenge for food.

According to Le Van Thanh, owner of Le Gia Seafood in Thanh Hoa City, rum bien can be harvested year-round, but the ideal season falls between March and June.

“Years ago, locals rarely consumed them due to their slimy and pungent nature, which made preparation laborious,” Thanh noted. “But now, they’re highly sought after.” During peak season, coastal residents in Nghe An and Thanh Hoa head out to collect them for sale.

Freshly caught rum bien retain water, with each kilogram containing about 6 to 10 pieces depending on size. Prices range from VND 300,000 to 400,000 per kilogram (USD 12 - 16).
Though found in many central provinces, rum bien is most abundant in Dien Chau (Nghe An). Photo: Thanh Tom Hum

rum biển cuộc sống dân biển.gif

Harvesting them requires patience. They live at various depths, with deeper-dwelling species being rarer and more expensive. When waves wash them ashore, collectors must move gently. Any agitation causes the rum to contract and bury deeper. Skilled hands are needed to retrieve the entire body and base.

In the water, their tentacles bloom like flowers. But once out, they retract into tight coils. Their colors range from ivory white to pale gray.

To clean them, the slime is removed by soaking in freshwater for 30 minutes, then scrubbing with rice husks, vinegar, lemon, and salt. After rinsing, they’re slit open to remove internal organs and washed again to remove sand. Cleaned rum is then blanched in boiling water with ginger and lemongrass to remove odors.

Locals also dry the cleaned rum bien to preserve them for year-round use. Dried ones must be soaked in warm water for hours, with water changed frequently, until they return to their plump, firm texture. The outer skin is then peeled, and the rum is blanched again before cooking.
Rum bien is increasingly popular, with the most beloved dish being banana stem stew. Photo: Tulinh Bui, Tran Van Quynh

rum biển xào củ chuối lâm phạm khánh.png
Rum bien stew with banana stem is best served hot. Photo: Lam Pham Khanh

Among the many dishes made with rum bien, rum om cu chuoi (banana stem stew) is the most iconic. Only tender banana stems are used. These are thinly sliced and soaked in salt water to remove sap and prevent browning. After blanching to remove bitterness, the stems become crisp and lightly sweet - similar to lotus root.

The next step involves sautéing shallots in pork fat or oil, then adding the banana stems with a splash of water to simmer. Once nearly done, rum bien is added and seasoned. Finally, herbs like la lot (wild betel leaf), tia to (perilla), and kinh gioi (Vietnamese balm) are stirred in before removing from heat.

Lam Tung from Hanoi, after tasting the dish in Nghe An, shared: “It’s an unusual but delicious combination. The banana stem adds crunch, while the fermented rice (me) brings a gentle tanginess. Chili, wild garlic, and pepper add heat. The rum itself is chewy but slightly slimy outside. Those with roe are rich and creamy. Thanks to the careful preparation, there’s no fishy taste at all.”

Thao Trinh