hi sally,

about the soup broth...vietnamese soup broth is relatively similiar to the chinese one.

i tend to make a big pot of stock. i mean a really big pot, about 10 cups of water. use 3 - 5 chicken bones (depends on the size), some spring onions (scallions), one knob of ginger, about 4 fat garlic clove ( washed and "wacked" with a kinfe), and some white whole pepercorns (i tend to add a handful asi we like it a lot.). If you are making it more fancier version, usually used in those cantonese superior wonton soup, then you need to add "dried shrimps" or "dried scallops", a good handful of them. since dried scallop are only available in chinese grocers and quite expensive, so i'd suggest you starting with the dried shrimps and see how you like the taste.

Bring the whole lot to a boil and simmer for about 3 hours. then you have a great stock. season to taste, fo course!