In my opinion, rice and fish sauce symbolize Vietnamese food culture.  Rice is the main staple of Vietnamese food. 

Rice grain is the easiest plant to grow in Vietnam. It is cheap. Rice is used for many types of food. Rice grain can be processed into rice flour. From rice flour, many other products such as bánh đa rice paper, rice noodles, rice cakes, and many desserts are produced.

Fish sauce is the most popular Vietnamese seasoning. Vietnam is bound by the South China Sea. There is a plethora of seafood. Fish sauce is made of different types of fish. Anchovies are the tastiest.

In northern Vietnam, all the Nguyễn children had to follow a certain eating etiquette. The eating etiquette is more complex than the contents of the meal itself.

The father is the head of the household. He consumes an appetizer such as a boiled chicken leg or chicken gizzards with a fine glass of rice wine while the rest of the family waits patiently.

Starting with the youngest, all children invite their older siblings and parents to start the meal before them. This custom of verbal invitation is called mời.

The father is always the first person to start the meal. When the meal is done, the children politely excuse themselves. The oldest girl clears the dishes.

The Vietnamese food is very simple yet adaptable to its environment. Storms and floods occurred at least once a year in the north and central Vietnam. Most northern and central Vietnamese are farmers.

Weather conditions cause Vietnamese farmers to be frugal. They adapt to their environment and ration their food for rainy days, literally.

Similarly, my family had to learn a new culture when we immigrated to America. American grocery stores do not stock Vietnamese ingredients. We adapted our recipes to what was available.