My mum bought frozen spinach soup. It was literally a block of water with spinach pieces and cream and seasonings in it. How does one cook it? By heating it. In truth, I don't understand why one would buy frozen soup, but at least it didn't have random ingredients like those in plastic containers. So, I added some water to it to dilute it and made a thinner soup. I then added it to some slightly-undercooked-just-the-way-I-like-it whole wheat pasta :)
The spinachy taste was not prevalent at all, except in the spinach pieces itself. Actually, if you had told me "oh this is a vegetable soup", I would not have guessed spinach. Leek, maybe, or just plain old spring onion. Or chives. Not spinach, though. The soup was creamy-ish though, before I diluted it.
I think I like tomato based pasta, more, mainly out of habit, though.