Leeks are a very mild onion. I can't remember ever eating them raw, however. They'd probably be a little tough. Cooked, they are the definition of tenderness.
Potato & leek soup, of course, is traditional and what I usually go for. Potato soup is just a little too . . . not much . . . without leeks. You can use a nice sauteed sweet onion but leeks have just about the texture of a potato once they have cooked for a moment. I like my potato soup where I can just about stand my spoon up in the middle of the bowl and not overcooked .
Thanks Steve. I have seen leeks at the store, just never tried them. I do love potato soup and make a pretty good pot of it, put it in the bowl, then top with grated cheese, chopped green onions and crumbled bacon. Yum. Will have to try the leeks. Sigh........that probably means something else I want to grow that I don't have room for..........