Garlic Cress (Peltaria alliacea) has a wonderful complex sharp taste, which is often described as mix between cress, mustard and garlic.
It has the highest growth rate of all my plants outside in winter (we had frost the whole week) and can be harvested from the snow.
It is distributed in Austria, Slowenia, Hungary and Romania, but not in Germany and Switzerland.
This is my plant, on 9.12. at -2°C to -7°C outside in winter and it grows unbraked:
...and in the short period of winter-sun:
http://www.pfaf.org/...ltaria+alliacea
http://www.kraeuter-...oetchen-Pflanze
The leaves and flowers can be used for spiciness in salads.