I made a big pot of soup and put a little of nearly everything I had in my refrigerator in it:
I put a little apple cider vinegar & 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
Loads of recipes call for adding sweet to counter bitter.
You can test by taking a bowl of soup and adding sugar until you are satisfied... or until you can't take neither the sweetness nor the bitterness.
Another option, in my experience, is adding salt. Loads of dishes improve greatly with the 'correct' amount of salt (correct is... whatever you prefer).
Basically, you should take a small amount of soup and test it. If you get it wrong, try again until you find the 'sweet spot'.
Also, if your soup does become too sweet, try adding salt to counter that...
