How to Use Vietnamese Coriander

I planted one Vietnamese Coriander plant this spring. It has really begun to grow and spread. I plant Chinese Coriander every year and this is nothing like the leaf variety.

That's right, it is completely different. It comes from a different plant family, and the growth characteristics and shape of the leaves are different.
It has the big advantage over leaf coriander or cilantro in that the herb regrows repeatedly after cutting. For herb gardeners with limited space indoors Vietnamese coriander is a godsend because just one or two pots can produce useable amounts of fresh leaves throughout a season. Cilantro, on the other hand, would have to be resown after each harvest.

What does one do with Vietnamese Coriander? It tastes nor smells nothing like leaf coriander. In fact, it has little taste.

Little taste? Hardly! Yes, it is different from cilantro, but not by much. But most definitely it has flavour and lots of it. I wonder if you have the correct plant. There are several closely related Polygonum species that look almost the same but do not have much flavour. Unmistakeably, Vietnamese coriander has a strong odour and flavour.

1. Do you allow it to seed and then use only the seed?

No, it never flowers and never sets seeds. Only the fresh leaves are used.

2. What dishes do you use it in?

In the West. it can be used as a substitute for fresh coriander (cilantro) although the flavour is not exactly the same. In Vietnam, it is not used in place of leaf coriander because the latter is generally widely available and there is no need to substitute.
The fresh leaves are used in soups.