How do I balance the bitterness of raddichio in soup? I made a big pot of soup and put a little of nearly everything I had in my refrigerator in it:


radicchio 
fresh green beans 
beets 
potato 
carrots 
garlic scapes
scallions 
tomatoes
yellow crookneck squash
swiss chard


I put a little apple cider vinegar &amp; sea salt in it and it has been simmering. I just tasted it and it was so bitter that I don't think my family will eat it. I think it must be coming from the radicchio...

Can it be salvaged?
Was the radicchio fresh? I'm not a big lettuce fan but I know a lot of greens can be bitter fresh (mustard greens, collards, calaloo) and can benefit from steaming, boiling or cooking first. 

Actually this website has a load of tips for reducing the bitterness in greens: http://www.justhungry.com/counteracting-bitterness-greens