I love this vegetable and it is in abundance in shops and veg boxes such as @riverford at the minute. It is related to the every day green broccoli that we get all year round, but has thinner stems and dark purple flowers. It is delicious steamed and served with olive oil or butter, or roasted in the oven with some parmesan cheese. Personally I find it has a more complex flavour than green broccoli and a more interesting texture as you eat the flowers, leaves and stem.
PSB is a great source of antioxidants which are important for a healthy immune system, and one study in 2012 found that PSB has a higher concentration of antioxidants than green broccoli. The antioxidants are retained in the vegetable as long as you don’t boil them or cook them for too long.
Link to research:
http://biohorizons.oxfordjournals.org/content/5/hzs004.full