there’s no code or correct combo per se but you would order one from each part of the menu. if you grew up in a vietnamese home and were lucky to have a parent that routinely cooks dinner then the typical every day meal would consist of a meat or salty (mon man) dish (such a braised dish such as caramelized pork/shrimp or catfish or chicken) along with a vegetable stir fry (mon xao) and a soup dish (mon canh), usually vegetable based soup. If you want to splurge or have a large group, can you get extras of mon man or mon xao.
All these dishes are very very traditional Vietnamese (it’s just not commonly served at restaurants of little saigon because these dishes are actually labeled as plain or commoner food “binh dan”) But as more and more little saigon restaurants become specialized and as the younger vietnamese generation cook less and less, these types of restaurants and dishes will be more valued.