It’s not often you come across a successful chef who cooks just one dish, but Sela Cham – a Siem Reap native and entrepreneur – has had a busy restaurant every night for the past three years. And there’s just one item on his menu: duck soup, made from a family recipe.

“When my wife and I started our restaurant, we served a variety of dishes,” Cham explains. “We realised that when there’s a lot of things on the menu, there’s a lot of waste. You spend a lot buying ingredients and refrigerating them but then don’t always use them.”

So Cham, who is a trained accountant, decided to shrink their menu to the single offering. It proved the key to their success. “This duck soup is unusual in this area,” Cham says. “I learned the recipe from my wife’s aunty who lives in Kratie, and I don’t know anywhere else in Siem Reap that makes it.”

Unusually for the area, Cham uses Muscovy ducks, which are black and darker than regular duck, and traditionally only eaten on special occasions. “In Siem Reap, it’s not very common to eat this duck, especially in a soup. Sometimes people make a traditional salad with Muscovy duck’s blood, but there aren’t even many places where you could order that.”

Cham’s soup is hearty and rich – a savoury broth that is a welcome addition to the cooler evenings the Cambodian “winter” has brought with it. It comes served bubbling over a small gas stove placed on the table, along with a heaped basket of ingredients which you add as you like.

Options include leafy green vegetables, mushrooms, baby corn, tofu, taro and noodles, as well as a tin of milk and a fertilised duck egg you can crack into the soup.

It’s not just the taste of the soup, however, that draws people to Cham’s restaurant. “This is a dish that you don’t eat alone,” he says. “You have to share it. Cambodians are very social, so they like to come with friends and family to eat soup together.”

As well as running this successful restaurant, Cham is a keen social entrepreneur managing an array of small projects. “It was hard to find enough Muscovy ducks to supply our restaurant, so I started working with local families,” Cham notes. “I give them a small investment so they can start raising ducks, and then I buy the ducks from them at market price.”

And a commitment to resourcefulness has led him to breed worms to make free duck feed for the families who rear his ducks and to burn used cooking oil blended with lemongrass oil to keep the mosquitoes away from his customers.

On any given evening, Cham’s restaurant is packed with everyone from young families and groups of friends to suited businessmen and army officials. As Cham proudly explains: “Everyone likes this soup, and we are happy to welcome everyone.”

Muscovy Duck Soup is located behind Kanta Bopha hospital, and is open every day from 3pm. A small pot of soup (2-3 people) costs $5, and a large pot (3-6 people) is $6.25.