One of my favorite side dishes in the whole world is a big pile of baby arugula lightly covered in an easy dressing of lemon juice, olive oil, salt and pepper with big shavings of parmesano reggiano on top. I tried it once at Bread in NYC and had to duplicate it myself (at 15.o0 a plate, it was an economic neccessity because I was addicted from the very first bite!).
It turns out that that very combination of greens, citrus and emollients is fantastic for your body. The arugula itself packs a punch with Vitamins A, B(almost all of them), C, as well as iron, magnesium, potassium, etc. The fresh lemon juice adds acidity and more Vitamin C, while the olive oil delivers that good for you monounsaturated fat we hear so much about. The parmesan cheese shavings are a luxury calorically and economically, so I often skip them and the salad is just as good.
If you've never tried arugula yet go for it. It's an awesome alternative to lettuce with a peppery taste that will keep you coming back for more.