Mizuna (pictured right) is also known as a Japanese mustard green. The crunchy greens are mildly bitter and peppery and very nutrient dense. The green works well raw as well as in cooked dishes. The texture is similar to flat leaf parsley. 
When using in a hot dish, add near the end of the cooking time as mizuna will wilts similar to spinach.
Slice and add to hot or cold pasta or potato salad or quinoa/rice dishes. The slightly peppery leaves add a lift. Top a hot out of the oven pizza with these sliced greens. The leaves mixed with other greens and tossed with bacon and a mustard vinaigrette is a wonderful match. 
Toss with noodles (rice noodles/udon noodles etc) and with soy sauce, ginger, garlic, sesame oil, green onions, shredded squash and thinly sliced peppers for a cold or room temperature lunch.