Dandelion greens are delightfully bitter. If you're using them in a salad, I would use them raw. But they are also tasty sauteed with garlic and served as a vegetable.
My understanding is that soaking anything for longer than a few minutes leaches out vitamins and nutrients. Sad for dandelion greens, which are supposed to be a nutrient powerhouse.
I would do a creamy, very oily, or sweet-citrus (orange, grapefruit) dressing to balance out that bitterness. But I'm with ChefJune in that I find the bitterness really appealing.
Does soaking in cold water leach nutrients? I would think that would hold more true for hot water...
Ah, well I looked it up and apparently it does...well I learned something new!
I like the bitterness in dandelion greens, too. I just give them a good washing before I use them. I even like them raw in a salad--cut them into thin slices and add some chopped onion. Fry bacon in olive oil. When the bacon is crisp and the oil hot, throw it over the greens. Season with salt, pepper, garlic and a bit of sugar. Toss with a good vinegar and/or lemon juice, and top with chopped hard boiled egg. You can use raddichio or curly endive for this salad as well.
I soaked them in water to revive them. It turns out that the soaking must have leached the bitterness out because they were not as bitter as I thought...still very good, though. Next time I will just wash thoroughly and cook right away.