I'd say roasted seaweed, but that's probably not as exotic as my family makes it sound, so I'll go with garlic-seasoned avocado. Most folks have guacamole, I just peel and eat the thing like a mango.
I... can't seem to recall anything that bitter I've eaten recently. I suppose there was that one plant I gave a nibble a few weeks ago... it smells really bad when crushed. I don't even know why I tried biting it.