Can you identify this?

This came in a punnet of Chinese vegies, but now I can't remember what I was supposed to do with it! Do I use it in salads or as a vegetable? As you can see, it's rather prolific - probably because I've eaten everything else around it!

I'm planning on finishing with most of the summer garden today - I'm going to toss the celery, silverbeet, handful of cherry tomatoes into the slow cooker with some onions, ground beef, mixed herbs and a bottle of the ubiquitous pasta sauce.