Hi,
you can cook it any healthy way you can think of, I mostly boil or microwave just by putting it in a bowl with either a lid or clingfilm over top with no water. I sometimes chuck frozen veg in the wok with frylight and soysauce with a sprinkle of crushed chillis. You can steam, oven cook and slow cook. Frozen veg is great and so much quicker, I used tinned mushrooms and carrots in an emergency if I run out.
xx