Japanese Water Pepper (Persicaria hydropiper)

Japanese Water Pepper (Persicaria hydropiper): a wonderful spice, used in many Japanese dishes but found throughout Indochina. If tasted fresh, it's perhaps too aggressive; an almost neutral sensation is followed by mustard, then by a very intense, sharp black pepper taste. Yet it's pleasant, like a wave that overwhelms you, but if we ride it by drying or blanching it for a few seconds, its true nature emerges: leaf peppers have a more ancestral flavor than tree peppers, which permeates the palate and reaches the throat, the back of the tongue, where there are more bitter and umami receptors, where we "choose" whether what we're chewing is edible or not. I really like this boundary, and the flavor of Hydropiper is all there.
In the field, or better yet, in water: in zone 2a in ponds and lakes, but it can easily be grown in pots, keeping the soil moist. Place it in full sun near bodies of water; in pots, prefer partial shade. The plant is an annual, completing its life cycle in one season. It tends to sow itself and will likely colonize the area adjacent to the crop in spring (if it finds sufficient moisture).
Please note : for easier germination, it's best to "stratify" the seeds. It's not difficult: leave them in the refrigerator immersed in a glass of water (2-4°C) for 5-6 days, making sure to change the water daily. This will speed up germination. Then sow at 20°C, keeping the substrate well moist.