I’ve recently had quite a few people ask the best way to cook veggies. I came across a study that backed up what I had answered, which is to steam them. The big thing though was that it also quantified what microwaving does.

From http://onlinelibrary.wiley.com/doi/10.1002/jsfa.1585/abstract

“Clear disadvantages were detected when broccoli was microwaved, namely high losses of flavonoids (97%), sinapic acid derivatives (74%) and caffeoyl-quinic acid derivatives (87%). Conventional boiling led to a significant loss of flavonoids (66%) from fresh raw broccoli, while high-pressure boiling caused considerable leaching (47%) of caffeoyl-quinic acid derivatives into the cooking water. On the other hand, steaming had minimal effects, in terms of loss, on both flavonoid and hydroxycinnamoyl derivative contents.”

I have a bigger article on the effects of microwaving your food coming later in the week, but for now best evidence shows steaming your veggies is best.

A cooking tip: when making rice I usually toss my veggies in to the pot for the last few minutes in effect steaming them with the rice. It can be done with fresh or frozen veggies.