Should always try for SF first but free is also fine. I try to balance my day with SF's as some meals don't seem to be right with veg to me.
I often have a veg soup made up in the fridge and try to eat that if I need something between meals but of course can't do this all the time. Other things you might like to try are SW quiche or fritatta which you can fill with whatever SF veg you've got.
HTH.
Denise
