“Nấu ngót” is a southern Vietnamese cooking term which involves cooking a clear (fish) soup with a lot of water and less salty and sour taste. This is to distinguish from sour soup which utilizes much sources of acidity in the soup. “Nấu ngót” cooking method, however, is more popular in northern Vietnam although northern Vietnamese do not name their cooking method.
Tomato is a common ingredients in this style of fish soup. Tomato adds umami flavor and a delicate sour taste. In northern Vietnam, dill is often added as a herb, which has aromatic smell to mask the fishy smell of the fish. In southern Vietnam, dill is not popular.
In Vietnamese, red snapper is called cá hồng, which literally means “pink fish” due to its pink color. The common red snapper species in Vietnam is Lutjanus sanguineus, which is often labeled as Humphead snapper to distinguish from other types of snapper. Humphead snapper occurs in the waters of the Indian Ocean and the Western Pacific Ocean. The fish is of economic value in Vietnam which accounts for 10 – 12% of fish production in the Gulf of Tonkin. There are actually 26 Lutjanus snapper species in Vietnam such as Lutjanus bohar (two-spot red snapper), Lutjanus johni (John’s snapper), Lutjanus argentimaculatus (mangrove red snapper), Lutjanus argentimaculatus (crimson snapper)…
The red snapper head soup has a mild sweet and sour taste, and the fish meat is very soft. In Vietnam, it is often served with dipping sauce made from fish sauce and crushed chili peppers.
Rinse off the white membrane inside the fish heads so that the fish is not fishy. Rub salt or vinegar lightly on the fish heads and then rinse again.
Sautee some minced garlic on a pot, then add the tomato wedges. Add a big bowl of water and bring to a boil on high heat. Reduce the heat to medium, then season with sugar, granule seasoning, fish sauce to your taste. Finally, add some lime juice, chopped scallions and celery, and turn off the heat.
Prepare a small bowl of dipping sauce with non-diluted fish sauce and crushed or sliced chili peppers.