Komatsuna, or Japanese mustard spinach, is a leafy vegetable. The tender leaves and stems can be eaten raw or cooked. It is grown almost exclusively in Japan, Taiwan, and South Korea. Other names include tendergreen and cai chua. It is most similar in taste to Tat Soi, and when big, the texture of the stems and leaves is reminiscent of Bok Choi.
Want to learn more? Look up Komatsuna on Wikipedia.
STORE: In a plastic bag in the crisper drawer